Can't select database

Like many others, I am new to WP and cannot get round the following message, whatever I try:

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

Are you sure it exists?
Does the user ishouldgetxxxxxx have permission to use the xxxxxx_ishouldgetoutmore_com database?
On some systems the name of your database is prefixed with your username, so it would be like username_xxxxxx_ishouldgetoutmore_com. Could that be the problem?

I have checked with my host (BT) that I have entered all the details correctly in wp-config.php…

What else am I missing?

Thanks.