I am having the same problem with linking. I get the link refused by document error as well. The exception is that I am relinking between 2 catparts. Is there special "rules" that allow you to link or relink? I have read that you can't use generative views to do it, among other things.
Catiajim has forgotten more than most of us know, he might have been mistaken on this one. I might as well recreate the drawing if I had to check every dimension.
The original question was relinking from a CATPart to a CATProduct. Does that workaround work for this case? I can understand how it would work from CATPart to CATPart or CATProduct to CATProduct, but not how it would work from CATPart to CATProduct or vice versa.