I believe you mentioned in the CB that you solved this problem. ("sorry, I just figured it out. The variable is not being passed properly.") I bet it's because you didn't properly quote and escape the contents of $item. I suggest that you use substitute
system("nzbget $item")
with
system('nzbget', $item)
It's safer since a shell isn't loaded, and you don't have to escape the contents of $item.