TOPIC: Error Message when submitting registration

I am having two problems.
I am doing a "free" single and group registration in Joomla 1.5. Everything works fine on the individual side but the group is having a few problems.

1.- After both group names are filled out and I go to next I get a Billing Information page with a Back and Next Step button. The event is free and this only happens on the Group registration.

2.- After the check data page when I go to next I get this message:
Notice: Undefined index: userId in E:\Web Sites\websitename\components\com_dtregister\controllers\message.php on line 225

Thank you for registering for the Work Kamper Boot Kamp on Jan 06, 2012. Your registration is being processed and you will be sent any information that you need for the event. You will also be receiving an email receipt of your registration.

The registration does not save. I have tried every setting and configuration I can think of but not sure what is wrong.

Thanks,

Jill