Bug than trying to add default relationship

Hi,

I'm getting Errors, than i try to add a default relationship by using "Add default".

The code drupal show's my is:

    * warning: Invalid argument supplied for foreach() in /htdocs/beta/modules/user/user.module on line 53.
    * user warning: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 1 query: SELECT * FROM d5users u WHERE in /htdocs/beta/includes/database.mysqli.inc on line 151.
    * warning: Invalid argument supplied for foreach() in /htdocs/beta/modules/user/user.module on line 53.
    * user warning: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 1 query: SELECT * FROM d5users u WHERE in /htdocs/beta/includes/database.mysqli.inc on line 151.

I added already the table's manually to the db but it doesn't work.
The stange thing is: I can add a default relationship, but a can't deside the Username, neither in the admin-interface, nor in the DB.

Can somebody help me?