When i created a registration form and checked CB intergration, only few fields were copied from CB profile, some fields are always missing (and I am sure they were all filled out in CB profiles).
Only the default form fields will get populated... no custom fields. If you have a default field that you manually created yourself in CB, maybe it is a different name than what DT Register is looking for. Also, make sure CB is set to use First Name / Last Name... not Single Name. Besides name and email, the fields DT Reg looks for are: