Data source name not found and no default driver specified

I know this may be a simple problem, but here it is:

I have SQL server express installed on Windows 2003 server (Testing) it works fine;

When I move it to my production server (Windows 2003) I get the error message"Data source name not found and no default driver specified "

The system DSN in ODBC connections works fine, or at least completes the test ok.

My application is written in Classic ASP

PLEASE HELP

Thanks

Can you provide your connection string?|||"Driver={SQL Server};Server=localhost;Database=TEST;Uid=MyUser;Pwd=MyPass;"