Hello - I am having a bit of a problem using the Paint Weights tool, which I have just started using. Basically I am having problems adjusting the weight for the selected polygon. When I try to select joints in the influence box of the tool options I can only see joints connected to the arm. How do I add this shape to joints on the rest of the skeleton? I read on another post that I had to erase the weights by changing the weight value to 0, but that didn't seem to have any effect. Obviously when I move the lower leg, this piece doesn't move at all.

Any help is much appreciated. Cheers.