Too am having this problem, I realize its an old thread but on my computer, I cannot get the joint connector to recognize both groups. I am using left cntrl but it will only allow me to select one of the two groups i'm trying to connect. Is there something i'm missing here? I've got a base and attched to it a "motor" thing. I'm trying to get connect it to a group that is placed directly above it on center with the motor button thing. When I select joint selector and use left control only 1 group will select. How do I get it to select the other group!