I have been working with this same technique for my models. first make sure that the ipt skeleton model in your iCopy assembly is set to reference in your BOM structure. Then check your skeleton wireframe sketch for any constraints. you can put driven dimensions but myself, I prefer to get rid of all of it. Your icopy will resize according to your points. When you Author your iCopy, choose points for your four corners then for any intermediate cross section beams, choose the coordinating line geometry.
It is good practice to try authoring your skeleton model by itself and inserting it into a sample frame to see if any errors occur before you put the extra work into adding frames, notches, ect.
Let me know if this works for you.
The Chaz