Before trying to link a table into Virtuoso, you should verify that the datasource is working correctly. Use a tool such as Microsoft Access, or ODBCtest to test your datasource. Your sanity check will verify that the datasource is correctly configured, that all necessary software is installed, that the database is running, and that there are no permission related problems. In addition, it will verify that the driver that you are using works correctly with the underlying datasource.

If there is a problem using a specific tool such as Microsoft Access with a specific driver, then that same problem will be manifested when the datasource is exposed via Virtuoso.