Sounds like you're trying to reference a custom iProperty called "OldName" in your iLogic code that doesn't exist. I'm assuming that if that were the case, you would have come to that conclusion as well. But without seeing your iLogic code and understanding it's purpose, it's difficult to know what might be wrong other than that.
Any chance I could look at the code? There are probably those one here who may be able to tell you what's wrong without seeing it. Do you refer to a property called "OldName" in your code?
I fixed it. This problem was strange because the solution required me to remove all of my content center parts for some reason. The "OldName" parameter was there in all of my parts(except content center) I still don't know why it was having trouble finding it because I've used this code on assemblies with Content Center parts before and had no problems.. The purpose of the code was to copy design an assembly along with all of its subsequent drawings to another folder. If I run into this problem again down the road I will post again but for now it works. Thanks for the reply though.
Glad that I could be of some help.
If I may ask, do you use autodesk vault? Vault has a feature that allows you to do what you're wanting to do quite easily. I would presume that if you have vault, you know about it since you explicitly said "copy design" which is the name of the command. Is there a reason that you wouldn't want to use the tool in vault? Are you, perhaps, trying to recreate the tool so that it can be more easily accessed?
Just kind of curious.