registration error

[vitalinka]

joomla 1.5.18
VM 1.1.4
Hello!
During the registration error is:
Critical: Failed to retrieve a valid USER ID when attempting to add a new user
vm_user_info table is empty. About Creating backend user works without problems.
In ps_shopper.php line 309, $ uid = ($ db-> f ('uid') == 0)? -1: $ Db-> f ('uid');
UID is 0
Where's the problem?