Lol.


He didn't want you to sign a message to prove your adress is your address.

He wanted the Transaction Id Number (short: TX ID) of the actual payment of the 0.33 BTC to your address.

Edit: Anyways: I just looked up your address on blockchain.info and it appears there were just two tarnsactions so far. You received 0.99 BTC with this transaction:
849e983e6ef89a280d3fa60f6592e8bb2b04dc7372bb5807b3cb6ea6df446e71
And then you've sent them straight away the next day in this transaction:
3b6a427a4438a4322963ffb095b2234c923e1ca2ed1cce9ffa0635b067e7f9d2