just to put in my two bits, this thing happened to me somewhere around 0.28.2-0.28.3, but thats when they where messing around with their db/layout/etc.
as for error messages, iirc you'll see the [No results] turn into [Aborted] if it fails.
yeah I know, very sudtle, but it's there...
I haven't had this problem since then (or if I have, it's so rare that I don't remember about it).
newzleech is at a bad time right now, several times it wont give any results for the past few hours, I hope the upgrades/redesigns are worth it
I do have a similar issue with binsearch results not queuing the rars (only .nfo .par2 + recovery) but I think that's a search engine issue not altbinz one.