NX 12 List and Angle issue

I am trying to drive an angle expression value down an assembly. I use Interpart expressions and link up to the top level assy expression. This works all fine. But I would like to be able to control the angles that can be set. Here I thought I would use a "List" expression type. I can create the list but I am unable to get the "driver" expression which is set an angle to accept the list input. Any suggestions on what I might be doing wrong here?