[Typo3] Yet another user register question

[Birk]

Hello all,
I have sr_feuserregister set up and running but I want to add two fields 
to the form.
I created a small ext as per the tutorial and modified the template.
Unfortunately I can't figure out why I get ###FIELD_TX_BIRK_CHECKA### on 
the create preview page.
I have tried a lower case version to the same effect.
If I set the field to required I see no eval errors but the * is black 
(not red as with user name or pass) and the form won't submit properly.
It just reloads.
I read the archived emails and I gather that I don't need to edit the 
php files but the symptoms of this lead be to believe that the extension 
may not have a clue about the extra fields added by my exdt to fe_users.
There is nothing in the object browser that gives me a clue.
Anyone have an idea what I am missing?
Thanks,
Lucas