How to solve link Errors?

Hello...

Can you please help me to solve the following link errors..........

ImportExportDoc.obj : error LNK2001: unresolved external symbol "public: __thiscall MeshVS_DataMapOfIntegerOwner::MeshVS_DataMapOfIntegerOwner(int)" (??0MeshVS_DataMapOfIntegerOwner@@QAE@H@Z)
ImportExportDoc.obj : error LNK2001: unresolved external symbol "public: __thiscall MeshVS_Mesh::MeshVS_Mesh(unsigned int)" (??0MeshVS_Mesh@@QAE@I@Z)
ImportExportDoc.obj : error LNK2001: unresolved external symbol "public: __thiscall MeshVS_DataMapOfIntegerBoolean::MeshVS_DataMapOfIntegerBoolean(int)" (??0MeshVS_DataMapOfIntegerBoolean@@QAE@H@Z)
ImportExportDoc.obj : error LNK2001: unresolved external symbol "public: __thiscall MeshVS_DataMapOfIntegerColor::MeshVS_DataMapOfIntegerColor(int)" (??0MeshVS_DataMapOfIntegerColor@@QAE@H@Z)
ImportExportDoc.obj : error LNK2001: unresolved external symbol "public: __thiscall MeshVS_DataMapOfIntegerMaterial::MeshVS_DataMapOfIntegerMaterial(int)" (??0MeshVS_DataMapOfIntegerMaterial@@QAE@H@Z)
ImportExportDoc.obj : error LNK2001: unresolved external symbol "public: void __thiscall MeshVS_Drawer::SetMaterial(int,class Graphic3d_MaterialAspect const &)" (?SetMaterial@MeshVS_Drawer@@QAEXHABVGraphic3d_MaterialAspect@@@Z)
ImportExportDoc.obj : error LNK2001: unresolved external symbol "public: void __thiscall MeshVS_Drawer::SetBoolean(int,unsigned int)" (?SetBoolean@MeshVS_Drawer@@QAEXHI@Z)
ImportExportDoc.obj : error LNK2001: unresolved external symbol "public: class Handle_MeshVS_Drawer __thiscall MeshVS_Mesh::GetDrawer(void)const " (?GetDrawer@MeshVS_Mesh@@QBE?AVHandle_MeshVS_Drawer@@XZ)
ImportExportDoc.obj : error LNK2001: unresolved external symbol "public: void __thiscall MeshVS_Mesh::AddBuilder(class Handle_MeshVS_PrsBuilder const &,unsigned int)" (?AddBuilder@MeshVS_Mesh@@QAEXABVHandle_MeshVS_PrsBuilder@@I@Z)
ImportExportDoc.obj : error LNK2001: unresolved external symbol "public: __thiscall MeshVS_MeshPrsBuilder::MeshVS_MeshPrsBuilder(class Handle_MeshVS_Mesh const &,int const &,class Handle_MeshVS_DataSource const &,int,int const &)" (??0MeshVS_MeshPrs
Builder@@QAE@ABVHandle_MeshVS_Mesh@@ABHABVHandle_MeshVS_DataSource@@H1@Z)
ImportExportDoc.obj : error LNK2001: unresolved external symbol "public: void __thiscall MeshVS_Mesh::SetDataSource(class Handle_MeshVS_DataSource const &)" (?SetDataSource@MeshVS_Mesh@@QAEXABVHandle_MeshVS_DataSource@@@Z)
ImportExportDoc.obj : error LNK2001: unresolved external symbol "public: __thiscall XSDRAWSTLVRML_DataSource::XSDRAWSTLVRML_DataSource(class Handle_StlMesh_Mesh const &)" (??0XSDRAWSTLVRML_DataSource@@QAE@ABVHandle_StlMesh_Mesh@@@Z)
../Debug/ImportExport.exe : fatal error LNK1120: 12 unresolved externals
Error executing link.exe.

If I am writing the code below I am getting the above link errors.....

Handle(StlMesh_Mesh) aSTLMesh = RWStl::ReadFile(aFile);
Handle( MeshVS_Mesh ) aMesh = new MeshVS_Mesh();
Handle( XSDRAWSTLVRML_DataSource ) aDS = new XSDRAWSTLVRML_DataSource( aSTLMesh );

aMesh->SetDataSource(aDS);
aMesh->AddBuilder( new MeshVS_MeshPrsBuilder( aMesh), Standard_True );
//False -> No selection
Handle_MeshVS_Drawer draw1 = aMesh->GetDrawer();
draw1->SetBoolean(MeshVS_DA_DisplayNodes,Standard_False);
//MeshVS_DrawerAttribute
Handle_MeshVS_Drawer draw2 = aMesh->GetDrawer();
draw2->SetBoolean(MeshVS_DA_ShowEdges,Standard_False);
Handle_MeshVS_Drawer draw3 = aMesh->GetDrawer();
draw3->SetMaterial(MeshVS_DA_FrontMaterial,DEFAULT_MATERIAL);

aMesh->SetColor(Quantity_NOC_AZURE);
aMesh->SetDisplayMode( MeshVS_DMF_Shading ); // Mode as defaut
aMesh->SetHilightMode( MeshVS_DMF_WireFrame ); // Wireframe as default hilight mode

anInteractiveContext->Display(aMesh);

Please tell me how to solve this error...........

Thanks in Advance
Suman