Negation

I’m really sorry if this is a very stupid question, but I’m frustrated by now.
Is it possible to negate a condition in brightscript?

I’ve tried these without any luck:

if(not var)
if(+var)
if(-var)
if(!var)

Is there a way to do this?
It is really frustrating having to use the following just because I want to negate the condition:

if(foo)
 (empty)
else
 something
end if
played=true
if not played then 
screen.addbutton(0,"play")
else
screen.addbutton(1,"replay")
end if