Oracle 10g Connection with ESS

[nviper]

I have an interesting problem. I have to connect a Filemaker database to an Oracle 10g database (Banner). The ODBC drivers are set and tested and they work. When I attempt to make the connection through Filemaker Server, it gives me an Oracle error (ORA-12154 which means that there is a problem with name resolution). On a hunch, I closed the database on Server, and opened it in Filemaker Pro 9 client and I was able to make the ODBC connection without a problem (I did this on the same computer). Any ideas? Everything that I have read indicates that you only need Server Advanced to have an external system connect with Filemaker but ESS does not require Server Advanced.