The problem may be trying to cross DWG file types. On the discussion
forums and in the knowledge base you can find mention of the fact that
Autodesk does not support customizations across DWG file types. You
are basically on your own. You may have to find someone who can
rewrite the lisps you need for the 2007/2008 dwg.
When we upgraded from 2002 to 2007 most of our existing customizations
worked, with the exception of a few lisp routines.