GT5 eats cars sometimes, this has happened to me once so far out of about 5 trades I've done. I sent a car and the guy never got it. He actually was nice enough to send me the trade car anyway!
The confusing thing when receiving a car is, that it doesn't show up as "1" (or n+1 when you had unused tickets before) in a red circle in the Car Delivery. Any yet, it's there when you go there.
In Community, take a look at the logs on his profile. It should say that he has received your car. If not, either you'll have to wait a bit longer or maybe it was "eaten" by the system....
The confusing thing when receiving a car is, that it doesn't show up as "1" (or n+1 when you had unused tickets before) in a red circle in the Car Delivery. Any yet, it's there when you go there.
LOL it doesnt happen straight away, usually it does but sometimes it just doesnt show up for a while and other times it wont show up at all but will be there from the beginnning (star or noise wont alert you)