PHP + IIS + WIN2K + ODBC Access Problem

Folks I have been trying to access an Oracle 7.x database through an ODBC DSN and it shows a message like: "cannot resolve service name: ...." Before that I have already tested the whole website with PHP 4.0.4 and Apache 1.3.14 in 2 different Win9x PCs and it all went *perfectly*. The only difference with that first scenario was that I used a Windows ODBC connection with an Access Database. On the other hand, working with WIN2K I also tried the ODBC connection outside the application (using the Oracle ODBC Tester) and it seemed to work fine. I also tried the same configuration in a different WIN2K box and the same error ocurred. I do not know what to do since I am in a race against the time... Any comments will be appreciated. My next steps will be update to a newer PHP release and tried with ODBC. I will also try a new version of my website, making the necessary changes for accessing Oracle directly. Wilman