My 17 year old just went through a frustrating experience and was hoping one of the knowledgeable folks here might have some idea what happened so we can avoid this in the future. He was trying to get on a one-way short flight from ORD to IND for same day travel. Online, AA said we had to purchase the ticket at the ticket counter so I sent him to the aiport. He got there with plenty of time to space (1 1/2 hour before departure) and bought the ticket at the counter. He received a printed boarding pass from the agent at the AA ticket counter, with a seat assignment, and his frequent flier and TSA security numbers all printed on the boarding pass. He went through security and waited for boarding. However, when went to board the gate agent scanned his boarding pass it was not valid. She checked her system and said his ticket had "expired". She told him he could not board and he had to come back home. I asked him to send me a picture of his boarding pass and I noticed in the upper section it said "not valid for travel" even though it go him through TSA and had a seat and ticket number printed?! Anyone have any idea what happened? Did the ticket counter just print the wrong ticket? I have traveled same day before and never had any issue like this.