Thanks for the feedback. It works now!!!!! I haven't figured out where I went wrong or what was causing the error, but some of the code must have been botched up, and NOW ParentSkeleton works perfectly.
I have some clues on what was wrong after making some changes to update the script. The dang script is 15 years old! Holy cow, I'm FREAKING OLD.
I resurrected it because long before targeted bones native in Moho, I scripted my own version. I was trying to recreate my script using the built-in targeted bone tools, but it appears my script... uh... er... has better features than the built-in tools. I am using this scripted version to have a reference to find a way to replicate my scripted bone targets with the built-in targeted bones. I've gotten close but not quite there yet.
The one cool thing my script does I can't quite replicate with the built-in targeting, is scaling down and up. In the bone settings, you can set the percentage of STRETCH only. Mine works by allowing scaling of any number of bones in a chain, both above and below the actual length of the bone and doesn't require any percentage set. The target bone both stretches and compresses the bone it controls, but does not interfere with the angle of that bone in the hierarchy.
For example, a leg in a walk or run cycle has a bend at the knee. I can target the calf to the foot and stretch, shrink, or rotate just the calf, and it has no effect on the thigh wich also has a target that can stretch, shrink, or change the angle of the thigh. It's awesome and allows some wicked cool exaggerated squash and stretch.
I am almost certain I should be able to replicate this with some sort of "out of the box" way of creating limb bone chains. Maybe with odd parenting, that isn't a basic chain like a standard leg or arm.
Okay, just rambling now. Anyway, parentskeleton is working again, thanks for listening.
