Getting LNK2001 && LNK2019 errors when I use lib functions

[Sushma]

CSiFtpConnection error LNK2001: unresolved external symbol "public:
virtual class ATL::CStringT<char,class StrTraitMFC_DLL<char,class
ATL::ChTraitsCRT<char> > > __thiscall
CSiException::BuildDefectInfoHelper(class ATL::CStringT<char,class
StrTraitMFC_DLL<char,class ATL::ChTraitsCRT<char> > > &)"
(?BuildDefectInfoHelper@CSiException@@UAE?AV?$CStr ingT@DV?$StrTraitMFC_DLL@DV?$ChTraitsCRT@D@ATL@@@@ @ATL@@AAV23@@Z)
CSiFtpConnection error LNK2019: unresolved external symbol
"__declspec(dllimport) public: __thiscall
CSiException::CSiException(class ATL::CStringT<char,class
StrTraitMFC_DLL<char,class ATL::ChTraitsCRT<char> > > const &,class
ATL::CStringT<char,class StrTraitMFC_DLL<char,class
ATL::ChTraitsCRT<char> > > const &)"
(__imp_??0CSiException@@QAE@ABV?$CStringT@DV?$StrT raitMFC_DLL@DV?$ChTraitsCRT@D@ATL@@@@@ATL@@0@Z)
referenced in function "public: int __thiscall
CSiFtpConnection::FindFileOrPDS(class ATL::CStringT<char,class
StrTraitMFC_DLL<char,class ATL::ChTraitsCRT<char> > >,bool)"
(?FindFileOrPDS@CSiFtpConnection@@QAEHV?$CStringT@ DV?$StrTraitMFC_DLL@DV?$ChTraitsCRT@D@ATL@@@@@ATL@ @_N@Z)