3ds bone connection question

Exactly what it says on a tile. I am rigging a model and need to connect two bones to a third bone, so the third bone will move in relation to the positions of both the previous bones. But whenever I use connect bone, it only acknowledges the second link, and not the first.
Here’s the gist of it:
Bone B is parented to bone A
Bone A is parented to the root
I need to make so that when Bone A moves, bone B moves with it while keeping its orientation towards the root.

Some screens:

http://i67.tinypic.com/2lntwl3.png[/t] [t]http://i68.tinypic.com/zsx05w.png

Basically, I need the piston to follow the bar below it as the mouth moves, but moving the mouth causes the piston to get in the position seen on the right.