assigning users to groups does not work?

Hello, am trying to assign user to a group. I go in the web interface and add a user. I go to /xwiki/bin/view/XWiki/XWikiAdminGroup and click on 'edit table'. The interface then shows this when i query the group: Group members Member xwiki:delbd XWiki.delbd xwiki:XWiki.delbd delbd However, if i log with this user, he doesn't appear to be part of the groups, he doesn't have the rights associated with the group. I did a step by step run of xwiki code in eclipse in XWikiRightServiceImpl and i found in line 300 that Collection glist = groupService.listGroupsForUser(name, context); return an empty list for user 'delbd' What is the problem? Did i fail in some way?