Is there any OTHER reason besides parenting hierarchy why one might not be able to choose a bone applying constraints ? I'm trying to rig a model and the right arm bones are not appearing in the dropdown nor can I apply constraints to them. I have tried moving them around the heirarchy and am pretty certain they are correct, yet I cannot associate anything to them, specifically translate/orient. I am tearing out my hair just trying to get this simple thing done yet I cannot see the bones in the dropdown no matter what I do. What am I overlooking? Please help !