I answered this one via PM, yeah?
Basically, it is because you need to define any global variables that you want vBACMPS to use.
In vBACMPS Options, add the following in the Global Variables box:
PHP Code:
nzb_greeting
nzb_greeting2
enhuser
enhthread
enhpost
On a related note, the custom welcome messages don't show on error pages.
I'm working on it when I have spare time.