Hi,
I think the connect tool has two options connect or parent, both of them use parenting of joints, their difference I think is what gets parented to what, and do things get moved.
For the parenting option things won't get moved and it does parenting on the two thing you select.
For the connect option things get moved and it does parenting on the one thing you select and the parent of the other thing.
If youv'e got something like this joints A,B,C, A parent of B, C by itself [http://flic.kr/p/bFySux](http://flic.kr/p/bFySux)
If you use connect option parent joint between B and C we get this (also C doesn't move) [http://flic.kr/p/bFySsk](http://flic.kr/p/bFySsk)
If you use connect option connect joint between B and C we get this (also C moved, so I moved it to the right to see it better) [http://flic.kr/p/bFySsZ](http://flic.kr/p/bFySsZ)
So connect is looking for B to have a parent, if it does it moves C to where B is and parents C to B's parent which is A.
I think the errror is happening if we try connect option connect between A and C [http://flic.kr/p/bFyStK](http://flic.kr/p/bFyStK)
So connect is looking for A to have a parent, but it doesn't so were getting an errror.
Hope this helps,
Regards,
Nate