Occasionally, we still seem to get questions about using LISP with AutoCAD Architecture (ACA) and MEP (AME). ACA and AME dropped DXF/LISP support since ADT 2004. This blog post gives you a little bit of history and reasoning behind the decision.
As new people joins, they sometimes assume whatever AutoCAD supports will be automatically extended to verticals. As it's been a while since we had this discussion, I'm bringing up this topic for the sake of people who are new to AutoCAD community.
The hard fact is that LISP uses DXF code to function, and ACA/MEP do not implement DXF. If you try to use LISP to access AEC objects, it simply does not return values. (Please see the earlier post for details.)
You can still use LISP as a vanilla AutoCAD. While AutoCAD is not adding any enhancement to LISP, the functionality it has already should remain. Same for VBA; ACA and AME do not support VBA/ActiveX. You can use it only to the level that access non-AEC objects.
If you are trying to customize ACA and AME, we recomend .NET API.