[Silentfood]

Make sure you've imported the database, and not just uploaded the SQL folder. This can be dne via phpMyAdmin.

Make sure you're using valid connection details, and make sure you're not using a database located on a server that denies outbound connections from other machines.

Make sure you're selecting the database according to what MySQL plugin you have.

And try enabling MySQL debug using the correct method via your MySQL plugin documentation.