If you attempt to use more than one local database connection in a workbook, you will see #VALUE for the results of one of them. When you use Jet/Debug, the function may calculate correctly. This is because when you run Debug, Jet closes all other local database connections to analyze the cell you have selected. The #VALUE occurs because each workbook can only have a single local database connection open at a time, so you can only include data from a single local database in a workbook. You can include data from multiple server database connections on the same workbook with no problems.
Only Navision users need to worry about debug and local database connections.