mysql problem

[dennism]

I've a RoundCube on this URL:
http://www.metteweibrecht.dk/webmail/index.php

As you see I just have a white page. I've debugged the problem and discovered. I've a webhotel at one.com, and they has given me this mySQL username and tablename: metteweibrecht_

When I inserts this into the "db_dsnw" variable in db.inc.php I have something like:
$rcmail_config['db_dsnw'] = 'mysql://metteweibrecht_:myPass@localhost/metteweibrecht_';

When I remove the "_" in the username I don't see the white page anymore - but I cannot login. So the "_" is the problem.
I hope you understand my problem!

What can I do to get this working with my bad username/tablename?