Vbulletin - database error on installation

im trying to install vBulletin 3.5.2 and im running the install script but keep getting this error:

The database has failed to connect because you do not have permission to connect to the server. Please confirm the values entered in the ‘includes/config.php’ file.

i’ve double checked at least 10 times now that the database user/pw/address is correct… any ideas on what the problem could be?