For example,

window->isdefinedby_() should not return null in

void window_test ()
{
    Registry  registry( SchemaInit );
    InstMgr   instance_list;
    STEPfile  sfile( registry, instance_list, "", false );

    sfile.ReadExchangeFile( "simple_wall.ifc" );
    sfile.Error().PrintContents(cout);

    Severity readSev = sfile.Error().severity();

    SdaiIfcwindow* window = (SdaiIfcwindow*)
        instance_list.GetApplication_instance(124-1);

    if ( window == ENTITY_NULL ) { cout << "NULL" << endl; exit(1); }

    SDAI_String global_id = (SDAI_String) window->globalid_();
    cout << "Window #" << window->StepFileId() << " " << global_id.c_str() << endl;

    EntityAggregate* aggr = window->isdefinedby_();  // there is a lot a properties for my window
    if(aggr) cout << aggr->EntryCount() << endl;     // so aggr should be defined here
    else cout << "NOT DEFINED" << endl;              // but "NOT DEFINED" is printed
}

Using the file simple_wall.ifc

ISO-10303-21;
HEADER;
FILE_DESCRIPTION (('ViewDefinition [CoordinationView, 
  QuantityTakeOffAddOnView]'), '2;1');
FILE_NAME ('example.ifc', '2008-08-01T21:53:56', 
  ('Architect'), ('Building Designer Office'), 
  'IFC Engine DLL version 1.02 beta', 
  'IFC Engine DLL version 1.02 beta', 'The authorising person');
FILE_SCHEMA (('IFC2X3'));
ENDSEC;

DATA;
#1 = IFCPROJECT('0YvctVUKr0kugbFTf53O9L', #2, 'Default Project', 
     'Description of Default Project', $, $, $, (#20), #7);
#2 = IFCOWNERHISTORY(#3, #6, $, .ADDED., $, $, $, 1217620436);
#3 = IFCPERSONANDORGANIZATION(#4, #5, $);
#4 = IFCPERSON('ID001', 'Bonsma', 'Peter', $, $, $, $, $);
#5 = IFCORGANIZATION($, 'TNO', 'TNO Building Innovation', $, $);
#6 = IFCAPPLICATION(#5, '0.10', 'Test Application', 'TA 1001');
#7 = IFCUNITASSIGNMENT((#8, #9, #10, #11, #15, #16, #17, #18, #19));
#8 = IFCSIUNIT(*, .LENGTHUNIT., $, .METRE.);
#9 = IFCSIUNIT(*, .AREAUNIT., $, .SQUARE_METRE.);
#10 = IFCSIUNIT(*, .VOLUMEUNIT., $, .CUBIC_METRE.);
#11 = IFCCONVERSIONBASEDUNIT(#12, .PLANEANGLEUNIT., 'DEGREE', #13);
#12 = IFCDIMENSIONALEXPONENTS(0, 0, 0, 0, 0, 0, 0);
#13 = IFCMEASUREWITHUNIT(IFCPLANEANGLEMEASURE(1.745E-2), #14);
#14 = IFCSIUNIT(*, .PLANEANGLEUNIT., $, .RADIAN.);
#15 = IFCSIUNIT(*, .SOLIDANGLEUNIT., $, .STERADIAN.);
#16 = IFCSIUNIT(*, .MASSUNIT., $, .GRAM.);
#17 = IFCSIUNIT(*, .TIMEUNIT., $, .SECOND.);
#18 = IFCSIUNIT(*, .THERMODYNAMICTEMPERATUREUNIT., $, .DEGREE_CELSIUS.);
#19 = IFCSIUNIT(*, .LUMINOUSINTENSITYUNIT., $, .LUMEN.);
#20 = IFCGEOMETRICREPRESENTATIONCONTEXT($, 'Model', 3, 1.000E-5, #21, $);
#21 = IFCAXIS2PLACEMENT3D(#22, $, $);
#22 = IFCCARTESIANPOINT((0., 0., 0.));
#23 = IFCSITE('3rNg_N55v4CRBpQVbZJoHB', #2, 'Default Site', 
      'Description of Default Site', $, #24, $, $, .ELEMENT., 
      (24, 28, 0), (54, 25, 0), $, $, $);
#24 = IFCLOCALPLACEMENT($, #25);
#25 = IFCAXIS2PLACEMENT3D(#26, #27, #28);
#26 = IFCCARTESIANPOINT((0., 0., 0.));
#27 = IFCDIRECTION((0., 0., 1.));
#28 = IFCDIRECTION((1., 0., 0.));
#29 = IFCBUILDING('0yf_M5JZv9QQXly4dq_zvI', #2, 'Default Building', 
      'Description of Default Building', $, #30, $, $, .ELEMENT., $, $, $);
#30 = IFCLOCALPLACEMENT(#24, #31);
#31 = IFCAXIS2PLACEMENT3D(#32, #33, #34);
#32 = IFCCARTESIANPOINT((0., 0., 0.));
#33 = IFCDIRECTION((0., 0., 1.));
#34 = IFCDIRECTION((1., 0., 0.));
#35 = IFCBUILDINGSTOREY('0C87kaqBXF$xpGmTZ7zxN$', #2, 'Default Building Storey', 
      'Description of Default Building Storey', $, #36, $, $, .ELEMENT., 0.);
#36 = IFCLOCALPLACEMENT(#30, #37);
#37 = IFCAXIS2PLACEMENT3D(#38, #39, #40);
#38 = IFCCARTESIANPOINT((0., 0., 0.));
#39 = IFCDIRECTION((0., 0., 1.));
#40 = IFCDIRECTION((1., 0., 0.));
#41 = IFCRELAGGREGATES('2168U9nPH5xB3UpDx_uK11', #2, 'BuildingContainer', 
      'BuildingContainer for BuildigStories', #29, (#35));
#42 = IFCRELAGGREGATES('3JuhmQJDj9xPnAnWoNb94X', #2, 'SiteContainer', 
      'SiteContainer For Buildings', #23, (#29));
#43 = IFCRELAGGREGATES('1Nl_BIjGLBke9u_6U3IWlW', #2, 'ProjectContainer', 
      'ProjectContainer for Sites', #1, (#23));
#44 = IFCRELCONTAINEDINSPATIALSTRUCTURE('2O_dMuDnr1Ahv28oR6ZVpr', #2, 
      'Default Building', 'Contents of Building Storey', (#45, #124), #35);
#45 = IFCWALLSTANDARDCASE('3vB2YO$MX4xv5uCqZZG05x', #2, 'Wall xyz', 
      'Description of Wall', $, #46, #51, $);
#46 = IFCLOCALPLACEMENT(#36, #47);
#47 = IFCAXIS2PLACEMENT3D(#48, #49, #50);
#48 = IFCCARTESIANPOINT((0., 0., 0.));
#49 = IFCDIRECTION((0., 0., 1.));
#50 = IFCDIRECTION((1., 0., 0.));
#51 = IFCPRODUCTDEFINITIONSHAPE($, $, (#79, #83));
#52 = IFCPROPERTYSET('18RtPv6efDwuUOMduCZ7rH', #2, 'Pset_WallCommon', $, 
      (#53, #54, #55, #56, #57, #58, #59, #60, #61, #62));
#53 = IFCPROPERTYSINGLEVALUE('Reference', 'Reference', IFCTEXT(''), $);
#54 = IFCPROPERTYSINGLEVALUE('AcousticRating', 'AcousticRating', IFCTEXT(''), $);
#55 = IFCPROPERTYSINGLEVALUE('FireRating', 'FireRating', IFCTEXT(''), $);
#56 = IFCPROPERTYSINGLEVALUE('Combustible', 'Combustible', IFCBOOLEAN(.F.), $);
#57 = IFCPROPERTYSINGLEVALUE('SurfaceSpreadOfFlame', 'SurfaceSpreadOfFlame', IFCTEXT(''), $);
#58 = IFCPROPERTYSINGLEVALUE('ThermalTransmittance', 'ThermalTransmittance', IFCREAL(2.400E-1), $);
#59 = IFCPROPERTYSINGLEVALUE('IsExternal', 'IsExternal', IFCBOOLEAN(.T.), $);
#60 = IFCPROPERTYSINGLEVALUE('ExtendToStructure', 'ExtendToStructure', IFCBOOLEAN(.F.), $);
#61 = IFCPROPERTYSINGLEVALUE('LoadBearing', 'LoadBearing', IFCBOOLEAN(.F.), $);
#62 = IFCPROPERTYSINGLEVALUE('Compartmentation', 'Compartmentation', IFCBOOLEAN(.F.), $);
#63 = IFCRELDEFINESBYPROPERTIES('3IxFuNHRvBDfMT6_FiWPEz', #2, $, $, (#45), #52);

#64 = IFCELEMENTQUANTITY('10m6qcXSj0Iu4RVOK1omPJ', #2, 'BaseQuantities', $, $, 
      (#65, #66, #67, #68, #69, #70, #71, #72));
#65 = IFCQUANTITYLENGTH('Width', 'Width', $, 3.000E-1);
#66 = IFCQUANTITYLENGTH('Lenght', 'Lenght', $, 5.);
#67 = IFCQUANTITYAREA('GrossSideArea', 'GrossSideArea', $, 11.500);
#68 = IFCQUANTITYAREA('NetSideArea', 'NetSideArea', $, 10.450);
#69 = IFCQUANTITYVOLUME('GrossVolume', 'GrossVolume', $, 3.450);
#70 = IFCQUANTITYVOLUME('NetVolume', 'NetVolume', $, 3.135);
#71 = IFCQUANTITYLENGTH('Height', 'Height', $, 2.300);
#72 = IFCQUANTITYAREA('GrossFootprintArea', 'GrossFootprintArea', $, 1.500);
#73 = IFCRELDEFINESBYPROPERTIES('0cpLgxVi9Ew8B08wF2Ql1w', #2, $, $, (#45), #64);
#74 = IFCRELASSOCIATESMATERIAL('2zeggBjk9A5wcc3k9CYqdL', #2, $, $, (#45), #75);
#75 = IFCMATERIALLAYERSETUSAGE(#76, .AXIS2., .POSITIVE., -1.500E-1);
#76 = IFCMATERIALLAYERSET((#77), $);
#77 = IFCMATERIALLAYER(#78, 3.000E-1, $);
#78 = IFCMATERIAL('Name of the material used for the wall');
#79 = IFCSHAPEREPRESENTATION(#20, 'Axis', 'Curve2D', (#80));
#80 = IFCPOLYLINE((#81, #82));
#81 = IFCCARTESIANPOINT((0., 1.500E-1));
#82 = IFCCARTESIANPOINT((5., 1.500E-1));
#83 = IFCSHAPEREPRESENTATION(#20, 'Body', 'SweptSolid', (#84));
#84 = IFCEXTRUDEDAREASOLID(#85, #92, #96, 2.300);
#85 = IFCARBITRARYCLOSEDPROFILEDEF(.AREA., $, #86);
#86 = IFCPOLYLINE((#87, #88, #89, #90, #91));
#87 = IFCCARTESIANPOINT((0., 0.));
#88 = IFCCARTESIANPOINT((0., 3.000E-1));
#89 = IFCCARTESIANPOINT((5., 3.000E-1));
#90 = IFCCARTESIANPOINT((5., 0.));
#91 = IFCCARTESIANPOINT((0., 0.));
#92 = IFCAXIS2PLACEMENT3D(#93, #94, #95);
#93 = IFCCARTESIANPOINT((0., 0., 0.));
#94 = IFCDIRECTION((0., 0., 1.));
#95 = IFCDIRECTION((1., 0., 0.));
#96 = IFCDIRECTION((0., 0., 1.));
#97 = IFCOPENINGELEMENT('2LcE70iQb51PEZynawyvuT', #2, 'Opening Element xyz', 
      'Description of Opening', $, #98, #103, $);
#98 = IFCLOCALPLACEMENT(#46, #99);
#99 = IFCAXIS2PLACEMENT3D(#100, #101, #102);
#100 = IFCCARTESIANPOINT((9.000E-1, 0., 2.500E-1));
#101 = IFCDIRECTION((0., 0., 1.));
#102 = IFCDIRECTION((1., 0., 0.));
#103 = IFCPRODUCTDEFINITIONSHAPE($, $, (#110));
#104 = IFCELEMENTQUANTITY('2yDPSWYWf319fWaWWvPxwA', #2, 'BaseQuantities', $, $, 
       (#105, #106, #107));
#105 = IFCQUANTITYLENGTH('Depth', 'Depth', $, 3.000E-1);
#106 = IFCQUANTITYLENGTH('Height', 'Height', $, 1.400);
#107 = IFCQUANTITYLENGTH('Width', 'Width', $, 7.500E-1);
#108 = IFCRELDEFINESBYPROPERTIES('2UEO1blXL9sPmb1AMeW7Ax', #2, $, $, (#97), #104);
#109 = IFCRELVOIDSELEMENT('3lR5koIT51Kwudkm5eIoTu', #2, $, $, #45, #97);
#110 = IFCSHAPEREPRESENTATION(#20, 'Body', 'SweptSolid', (#111));
#111 = IFCEXTRUDEDAREASOLID(#112, #119, #123, 1.400);
#112 = IFCARBITRARYCLOSEDPROFILEDEF(.AREA., $, #113);
#113 = IFCPOLYLINE((#114, #115, #116, #117, #118));
#114 = IFCCARTESIANPOINT((0., 0.));
#115 = IFCCARTESIANPOINT((0., 3.000E-1));
#116 = IFCCARTESIANPOINT((7.500E-1, 3.000E-1));
#117 = IFCCARTESIANPOINT((7.500E-1, 0.));
#118 = IFCCARTESIANPOINT((0., 0.));
#119 = IFCAXIS2PLACEMENT3D(#120, #121, #122);
#120 = IFCCARTESIANPOINT((0., 0., 0.));
#121 = IFCDIRECTION((0., 0., 1.));
#122 = IFCDIRECTION((1., 0., 0.));
#123 = IFCDIRECTION((0., 0., 1.));
#124 = IFCWINDOW('0LV8Pid0X3IA3jJLVDPidY', #2, 'Window xyz', 
       'Description of Window', $, #125, #130, $, 1.400, 7.500E-1);
#125 = IFCLOCALPLACEMENT(#98, #126);
#126 = IFCAXIS2PLACEMENT3D(#127, #128, #129);
#127 = IFCCARTESIANPOINT((0., 1.000E-1, 0.));
#128 = IFCDIRECTION((0., 0., 1.));
#129 = IFCDIRECTION((1., 0., 0.));
#130 = IFCPRODUCTDEFINITIONSHAPE($, $, (#150));
#131 = IFCRELFILLSELEMENT('1CDlLMVMv1qw1giUXpQgxI', #2, $, $, #97, #124);
#132 = IFCPROPERTYSET('0fhz_bHU54xB$tXHjHPUZl', #2, 'Pset_WindowCommon', $, 
       (#133, #134, #135, #136, #137, #138, #139, #140, #141, #142, #143, #144));
#133 = IFCPROPERTYSINGLEVALUE('Reference', 'Reference', IFCTEXT(''), $);
#134 = IFCPROPERTYSINGLEVALUE('FireRating', 'FireRating', IFCTEXT(''), $);
#135 = IFCPROPERTYSINGLEVALUE('AcousticRating', 'AcousticRating', IFCTEXT(''), $);
#136 = IFCPROPERTYSINGLEVALUE('SecurityRating', 'SecurityRating', IFCTEXT(''), $);
#137 = IFCPROPERTYSINGLEVALUE('IsExternal', 'IsExternal', IFCBOOLEAN(.T.), $);
#138 = IFCPROPERTYSINGLEVALUE('Infiltration', 'Infiltration', IFCBOOLEAN(.F.), $);
#139 = IFCPROPERTYSINGLEVALUE('ThermalTransmittance', 'ThermalTransmittance', IFCREAL(2.400E-1), $);
#140 = IFCPROPERTYSINGLEVALUE('GlazingAresFraction', 'GlazingAresFraction', IFCREAL(7.000E-1), $);
#141 = IFCPROPERTYSINGLEVALUE('HandicapAccessible', 'HandicapAccessible', IFCBOOLEAN(.F.), $);
#142 = IFCPROPERTYSINGLEVALUE('FireExit', 'FireExit', IFCBOOLEAN(.F.), $);
#143 = IFCPROPERTYSINGLEVALUE('SelfClosing', 'SelfClosing', IFCBOOLEAN(.F.), $);
#144 = IFCPROPERTYSINGLEVALUE('SmokeStop', 'SmokeStop', IFCBOOLEAN(.F.), $);
#145 = IFCRELDEFINESBYPROPERTIES('2fHMxamlj5DvGvEKfCk8nj', #2, $, $, (#124), #132);
#146 = IFCELEMENTQUANTITY('0bB_7AP5v5OBZ90TDvo0Fo', #2, 'BaseQuantities', $, $, (#147, #148));

#147 = IFCQUANTITYLENGTH('Height', 'Height', $, 1.400);
#148 = IFCQUANTITYLENGTH('Width', 'Width', $, 7.500E-1);
#149 = IFCRELDEFINESBYPROPERTIES('0FmgI0DRX49OXL_$Wa2P1E', #2, $, $, (#124), #146);
#150 = IFCSHAPEREPRESENTATION(#20, 'Body', 'SweptSolid', (#151));
#151 = IFCEXTRUDEDAREASOLID(#152, #159, #163, 1.400);
#152 = IFCARBITRARYCLOSEDPROFILEDEF(.AREA., $, #153);
#153 = IFCPOLYLINE((#154, #155, #156, #157, #158));
#154 = IFCCARTESIANPOINT((0., 0.));
#155 = IFCCARTESIANPOINT((0., 1.000E-1));
#156 = IFCCARTESIANPOINT((7.500E-1, 1.000E-1));
#157 = IFCCARTESIANPOINT((7.500E-1, 0.));
#158 = IFCCARTESIANPOINT((0., 0.));
#159 = IFCAXIS2PLACEMENT3D(#160, #161, #162);
#160 = IFCCARTESIANPOINT((0., 0., 0.));
#161 = IFCDIRECTION((0., 0., 1.));
#162 = IFCDIRECTION((1., 0., 0.));
#163 = IFCDIRECTION((0., 0., 1.));
ENDSEC;
END-ISO-10303-21;

Depends upon issue #199