Dude. First of all Any concave brush will give you an error right away. And it's obvious Skals didn't understand what you said because i barely understood it myself.
Anyway Skals, http://twhl.co.za/forums.php?thread=14161 , That's the compilator and it's REALLY easy to use and i highly recommend it. When you get everything set up (It's self-explanatory really, ) go to the vis tab, and hit the full box.
Then just hit compile and you're done!
And if there's any error whatsoever while compiling, The compile log HIGHLIGHTS the errors in red