TOPIC: Error messages in some lists display (DT-Reg 3.0.9a - Joomla 3.3.3)

hello there at DTH Development,

I recently installed DT register (3.0.9a) on a Joomla 3.3.3.
Most of things are working correctly but I found some error in several administration pages as :
- Categories
- Fields (can't view existing fields - only error messages)
- Export CSV
List are not displayed correctly and I have error messages.
Unfortunately I cannot add any image of these massages to this post.

Any idea about what happens ?
Thanks in anticipation for your help !