how to get the feature type pointer from the LPDISPATCH

dear all,

i used the codes: pModelDocExtension->SelectByID2(auT("Extrude2"), auT("BODYFEATURE"),0,

0, 0, FALSE, 0, NULL, swSelectOptionDefault, &retval); pModelDoc->get_ISelectionManager(&pSelMgr); pSelMgr->GetSelectedObject6(1, 0, &Retvala);

to access the feature named extrude2 from an active part, after that i want to access the selected feature, but cannot do it in the below way as: LPFEATURE pCurFeature; pCurFeature = (IFeature*)Retvala; LPFEATURE pSubFeat = NULL; pCurFeature->IGetFirstSubFeature(&pSubFeat);

whenever i ran it, there are errors

BTW, i am using the dll to do the solidworks API,i don't know how to debug the codes which would create dll file, anyone can give me a hint?

thanks

regards SY