unable acces database

[Cottelletje]

when i installed it i get this error

The installer was unable to access the "***" database. With some hosts, you have to create the database in your administration panel before SMF can use it. Some also add prefixes - like your username - to your database names.

but i now the username is used as prefix and i write it username_namedatabse but it still gives this error
and i created that database in my admin panel(cpanel)