Sometimes error messages aren't very specific...perhaps at times they are *too* specific for non-programmers to comprehend? Anyway, here is an example of one that you can get when trying to connect to an Excel spreadsheet using FDO:
The solution? Re-create (or Edit existing) DSN in ODBC Administrator, remembering the ever-crucial step of [Select Workbook].
After this, connect again to the DSN and do what you need to to [Add to Map]. You should be a happy camper!