Multiple problems: Rigged arm & hand with elbow corrective shape key

Question

I have multiple Problems. :/

1. Trying to create a corrective shape key driver for the elbow, I managed to create the shape key itself without a problem. assigning it to a driver I realized, that the value of the driver always remained 0. Even when moving the FK_bone, thus deforming the forearm successfully, the value did not change, so neither did the shape of the elbow. Please help me with that.

2. Upon trying to figure it out myself, I played around with the roll of the different bones (left arm and left hand) in edit mode. I did this trying to make sense out of why the value did not change on the driver. As a result I can now not move the forearm along the global or the local z-Axis. Please help with this one too.

I am trying to teach myself Blender while I have a full schedule, plus this is my first Character created in this programme, so please excuse obvious mistakes or an unclean file.

Thank you for your help :)

Here is the file:

P.S. His right arm is unrotated or rolled. His right arm is the maximum movement I would like the shape key to have as value 1.

Answer 1

ORG-forearm.L is not rotating anymore simply because its rotation values are locked (picture n. 1)

In your actual setup the rotation of this bone on his local Z axis has a negative value, so you can get your corrective shape key work with a negative expression (multiplied by 0.5 for having maximum effect roughly at full rotation; picure n. 2).