Cannot get wordpress to pick up wordpress database

We host as lot of websites from one of our hosting clients and we have not been able to wordpress to load properly into the clients domian.

Every client has their own folder for their website ex: public_html/client/wordpress.

When I go to http://www.client.com/wordpress and attempt to configure I keep getting :

We were able to connect to the database server (which means your username and password is okay) but not able to select the client_wordpress database.

Any ideas of what I am doing wrong?