[Gimp-user] script-fu: illegal function?

[Gary Aitken <gimp dreamchaser org>]

When I try the following in the script-fu console:

((define (find-dot txt txtLen offset) (print "foo")) (find-dot "abcd.ef" 7 1))
"foo"
Error: illegal function 

The find-dot macro obviously exists and is being executed.
So what is the illegal function it is complaining about?

Thanks