How do I use CAS variables in a Program?

[Han]

The CAS() command is a merely a "wrapper" command that enables non-CAS programs (i.e. "Home" programs) to execute CAS commands as if one were in the CAS view. The same goes for CAS.command() or CAS.object.

Since you used the #cas ... #end then you have already declared that everything enclosed within is to be treated as if run from the CAS view. So CAS.command() or CAS.object or even CAS("command or expression") is not only redundant but introduces possible conflicts in environments (CAS vs non-CAS).