As a documentation of what the problem was and how i fixed it i will explain what i did.
the names are taken from Joe's rigging 2 disk 1
When i set the IK/FK slider to FK and selected the bone "Nate_Forearm1R" and tried to rotate it on (P) it would not move.
The IK worked perfectly and the all the other FK joints worked fine too.
I found that by bypassing the IK solver variable on Nate's arm i could get the bone in question working again. This led me to think that i had set up the IK wrong. after careful examination i found no errors, and then proceeded to work my way back though the variables, as i was inspecting the IK/FK fader variable i discovered that when i was redoing it i had somehow added the Bicep1R bone twice to the expresion and had left out the Forarm1R bone in the process. Smelling a rat i decided to investigate closer, indeed i had the same error in my original setup, fixing this solved the problem, i was not fading the IK of the forarm bone and so it was not responding to FK commands.
ok i'm setteing up the arms on Nate, and i finished the video with no obvious errors occuring, everything was working, except i then noticed that when the slider was set to FK the bone "Nate_Forearm1R' which is supposed to be the second FK controller in his arm wouldn't respont to pitch. it responds fine as soon as i bypass the "Nate_IKAlignHandR" Variable but the minute i turn it back on it stops working, the edit shpere spins but the bone doesnt move.
i've double checked and all my variables are in order, i'm also pretty sure that i set the bones up right in the first place, but i may be wrong and got the coordinate thing messed up again, though i dont think that i did....
what is likely to be causing this, are there any stats or images that i can post to help solve this problem? let me know and i'll post them :)