WCF service error when using MySql.Data.MySqlClient (no replies)

I have a fully functional WCF webservice hosted in iis7 on Win Server 2008 machine. The problem is when I try to implement mysql calls to a method in the service. The method works fine when debugging in vs, all the mysql methods and the call to the database works as it should, but when deploying it to the server I get "The server encountered an error processing the request" error. If I remove everything in the method but for example

string connStr = "{connection details}"; MySqlConnection conn = new MySqlConnection(connStr);

and try to run the service, I still get the same error...

I've run out of ideas and really need your help!