Custom Customer "Fields" won't work/Customer groups default not working

[cowboy-headquarters]

We tried to set some new customer "field" (don't know the correct english translation), for the user/customer registration form. Yet even though they are set to "published" they do not show in the regristration form. It allways shows the form for anonymous users. We looked at the customer groups and then set the default group to default and set the anonymous group to "not published". But all that happens now is a error message saying, "no default user/customer group set" and the form still shows none of our custom "fields" and attributes.

So, what do I have to do, to fix this?

PS: Virtuemart v. 2.0.18a, Joomla 2.5.8 und PHP 5.3