MonoX actually uses the credentials you enter on a previous screen to connect to the db server. Data from the config file is not used during the installation process, as they are written when it is finished. If you entered the sa password correctly, everything should work. In any case, you could use the trace utility in sql management studio to see if MonoX reaches your server and under which credentials. Alternatively, one of our support technicians could connect to your machine to diagnose your problems.