Actually, avast! has already detected one of your Zlob samples but it’s detected during the installation process (don’t do/try it on your machine) or the extraction, not by its installer.

As fas as I know, Zlob has a countless variants, I think they have been released several variants a day, no AV software can detect them all, even AntiVir which has been dedicated themselves to heuristic/generic detection in order to fight against a Zlob trojan variants, I’ve also noticed that some vendors such as AVG has been released a signature for a Zlob trojan variants very very often.