Getting compliation error while adding TDAPIOLELIB.dll and using QCResourcefolder factory in UFT API

After adding a reference to API script OTA Com Type Library to connect QC from API test scripts , giving errors (Could not load type 'TDAPIOLELib.ITDConnection11' from assembly 'Interop.TDAPIOLELib, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null'.)

We would like to develop some custom activites of Resource Download from QC and while using TDAPIOLELIb.dll its giving compilation errors as its not recognizing QCResourceFolderFactory  and TDConnection etc.,

Please let me know.