It took me two weeks to get a call for a class. I had given up also. Then the call came in. One guy in my class said he finally sent an email and was told he was in the pool. No notification he was in it, he never would have known had he not emailed. That does not mean you need to immediately contact L or D (whoever emailed you the information for the interview, etc) but I can be pretty certain they would not mind an email if it has been 3 weeks or a month and you still haven't heard anything. Despite the airline flying all around the world, it still feels like a mom and pop operation, and stuff like this seems to fall through the cracks. Good luck!

-T