Hi guys

I decided to have a go at converting a model to GTA from Forza 4 so I've got so far using a tutorial but I'm now stuck at the stage where you convert the parts to compounds because for whatever reason the button to do it just isn't there for me. I'm using a trial version of zmodeler but I wouldn't have thought that would be the issue. If anyone knows how I can sort this, pls halp.