OK, I am new to rigging, so hopefully this is an easy question to answer. I've got a finger rig, which I made by following a book, to be specific, the Second Edition of Oliver Villar's book, Learning Blender. Here's a picture.
The big bone, called C_Finger_1, is the bone I use to control the finger. When I rotate it, it rotates all the fingers, as it should.
However, when I scale it down, it should flex the finger, but it doesn't. The fingers do nothing, except they flip when I scale the C_Finger_1 bone past -1.
I am very much a beginner to this sort of thing. Could anyone point me in the right direction?