Problem solved.
Just removed the reference, saved the project, restarted the project and
added again the same reference.
Any thoughts on that?
Jack

"Jack" <replyto@it wrote in message
...
Hello,
My app is using Excel spreadsheet.
User has a choice of preselecting some of the sheet's columns.
Now:
Excel is using letters as the visual indexing, of the columns but when
programming the corresponding number (A --1, B --2..., AA--28, AB--29
etc) must be used..

What will be the best method of converting those letters into numbers?
Jack