I'll say thank you, too, LITSA. I recently was the victim of a bad trade: I sent out $32.00 worth of coupons and got nothing in return so far and it has been 3 weeks. And this was someone I've traded with before and trusted!
If for some reason you will be late or cannot honor a trade, PLEASE tell the person. We should all be mature and understanding enough to realize life can take a turn and things will be delayed sometimes. But don't leave someone hanging for 3 weeks with not even an explanation!