Data connection problem between Assess front end and SQL server behind firewall

I have an Access 2000 front end (on win 98) for a SQL 2000 database (on win 2000 server) behind a firewall. A port (1433) was opened for connecting the Access front end to the SQL database. The odbc system DSN connection showed data source "TESTS COMPLETED SUCCESSFULLY!". However, the Access front end still does not work. The same Access program works well within the firewall. Could anyone tell me what could possible be wrong?What error does Access return?