I suspect the problem is the variable isn't initalised in the template you're trying to add the condition to.
I've been trying to wrap my head around this, but by my understanding:
In vB3 variables such as usergroup were globalised and you could use them in a conditional almost anywhere on a page.
vB4 goes about processing of variables in a totally different way. If you want to use a variable in any template, it has to be initialised for that particular template first.
Don't ask me the syntax needed on how to do it - as I say I've only just wrapped my head around the concept. At this point (with the unpredictable nature of vB4 development) I'm trying to avoid that level of modifying like the plague.