It would only work at the box office if A the ticket was bought there and B you have the conformation number which I am guessing you don't have considering the fact that most tickets sold through don't have the seller tell you the conformation number.
By the by alfgiotir, what's the lowest your willing to sell the ticket for?
"If you try to shag my husband while I am still alive, I will shove the art of motorcycle maintenance up your rancid little Cu**. That's a good dear"
Tom Stoppard's Rock N Roll