jittering on clavicle control

[benjaminiholloway]

While following AntCGI's real time creature tutorial series, I could not get the clavicles to behave correctly. the tutorial method I was attempting was to parent constrain only the translations of the clavicle to the spine IK and FK systems, and then to use an aim constraint to point the clavicle at shoulder root. However trying to do anything with the shoulder after this returns the error "// Warning: Cycle on 'RT_Coracoid_BJ.parentInverseMatrix[0]' may not evaluate as expected. (Use 'cycleCheck -e off' to disable this warning.)" moving any parent of the shoulder has a jitter, and zeroing out controls causes the clavicle to rotate out of place. these bugs don't effect the values, and moving the root back and forth or switching back and forth from IK and FK fix the bad rotations, but  constantly having to go back and fix the shoulders is getting old fast! can anyone help me find a solution or cause to this problem?

[mcw0]

Any time there's jittering in joints, it's a clear sign you have a cycle.  And as proof, you are getting the warning of a cycle.  It's a chicken/egg issue.  In a cycle, it's unclear what needs to happen first.  What is driving what.  You need to select the node that Maya is warning you about and check your graph.  Remove the cycle and all will be fine.