I have the same error, but I'm using the updated Plugin (3.2.1) and Jomsocial 2.2.1.
Can you tell me what type of configuration causes this Error?
//EDIT:
I got the Problem fixed

It is an Jomsocial Issue not a problem with JFBConnect.
With Jomsocial 2.2.2 the bug is fixed
For all with jomsocial 2.2.1 here is the patch:
www.jomsocial.com/forum/index.php?f=3&t=...42362adf9f02bee7d2fd