What OS is FileMaker Server running on? What version of FileMaker Server? If the OS is Windows and the it's FileMaker Server 11, a common issue is setting up the DSN using the 64bit ODBC manager instead of the 32bit ODBC manager. You also need to make sure the DSN is set up as a system DSN and not User DSN. I don't know if newer versions of FileMaker server have the same issue regarding 32bit vs. 64bit.