I've tried this:
'start Excel app
Dim exApp As Microsoft.Office.Interop.Excel.Application
exApp = CreateObject("Excel.Application")
' load excel document
exApp.Workbooks.Open(fname)
Dim exSheet As Microsoft.Office.Interop.Excel.Worksheet
exSheet = exApp.Workbooks(1).Worksheets(1)
and than, for example accessing "C3" cell:
Dim b As String
b = exSheet.Cells("A3")
or:
b = exSheet.Cells(3,3)
and it throws me an exception. I'm feeling that I'm doing something wrong with the object access, but this method worked in embedded VB, and do not works in .net. Also, tried to google the exception code, with no relevant result.