You path to acces NSF file in LS or function is invalid.
The path have to be related to your Notes or Domino data installation path.
Suppose you have install Notes software in C:\LOTUS\NOTES\
and your NSF data in D:\LOTUS\DATA
So If you want to acces a file present in D:\LOTUS\DATA\MyFolder\MyNSFToReach.NSF, your acces path will be
An example in LS
Dim session as New NotesSession
Dim myDb as NotesDatabase
Set myDb = session.GetDatabase( “MyDominoServerName” , “MyFolder\MyNSFToReach.NSF” , False)