Finger Isn't Flexing 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?
You need to:


Deactivate the IK's rotation option (don't know what is for, it's off by default):





Bend the bones a bit in Edit mode so that Blender knows how to flex it.





Once bent, correct the Pole Angle of the IK bone: