Help with implementing Shape Key Drivers I was wondering if anyone could help me out with figuring out how to use Shape Key Drivers for the model that I've been working on for quite a while.

Basically, I need my model's head to be able to tilt upwards, going from this...



...to this...



...without any problematic mesh deformations, like in the picture below, or the head losing it's general shape, which has been quite a bit of problem for me while trying to setup the head.



The only option I've found thus far in getting the head to bend in the way that I want it to has been to use Shape Keys to iron out the deformation problem near the neck.  The problem now, however, is that I still need to somehow get the Shape Key to work when the "muzzle" bone is rotated upwards.  I've been trying to apply a Shape Key Driver to see if that would work, but unfortunately, I can't seem get the driver to work properly and looking up tutorials on Shape Key Drivers hasn't exactly provided much help either.

I greatly need help in how to properly setup a Shape Key Driver, and any help on this matter would be greatly appreciated.

EDIT:

After failing to properly implement the Shape Key Driver, I've noticed that I am no longer able to manipulate the Shape Key Value.  Every time I try to move the slider I get an error message at the top of the screen reading "Can't edit driven number value, see graph editor for the driver setup".  I'm not sure what the error message is referring to or whether or not it helps in identifying why I'm unable to implement the Shape Key Driver but I thought it would worth mentioning anyway.

Also, I'd appreciate it if people would stay focused on the subject of how to implement Shape Key Drivers. I'm well aware that the way the armature for the head is set up is unconventional to say the least, but unless there is something seriously wrong that would cause a major problem with setting up the Drivers, I would much prefer to keep the focus on the main subject at hand.
You need to know, that weight are not describe how bone influence on mesh. Instead, weight describes how the effect on the mesh is distributed between the bones. So if you have setup only one bone, 100% affects is from this bone even if you set 0.0001 weight. 

Also, you can get nicer and smother results if you set armature modifier before subsurf.