I have the same issue. I have checked settings and they all seem to be set properly... But when a form i submited, the same page reloads, and no records add to the back end.
I have a message setup if users are added wait list.
I also notice that when i click on Waitlists (in the back end), then choose any event from the list, the screen refreshes, and the event list is then empty.
I have to click on Waitlists again to refresh the event list... Hope this helps diagnose the problem.
We have implemented this fix in the new release that is almost done. I went ahead and just added the fix to the current package. You can download it now. The file that needs replaced is:
/components/com_dtregister/dtregister.php