Under the Managed C++ platform,I use Autodesk::AutoCAD::ApplicationServices::Application::DocumentManager->MdiActiveDocument->Editor->GetEntity() method to get the AcDbDimension instance id.and then I use acdbGetDimAssocId function to get the relative AcDbDimAssoc instance id. But I failed to get the AcDbDimAssoc instance, because the acdbOpenObject function can not obtain the illegal instance.
