I just had a guy do that to me on here as well. I will not name any names but they wanted to trade for a ball and was very responsive to PMs for the deal. Set up the deal and agreed a trade. I sent my tracking number right away, but I never drop off the box until the other party provides at least a tracking number (although they can void it, they at least made an attempt). This person said they would get the number the next day for me, when they shipped it. One day goes by no number, two days no number...etc. Sent about 4 or 5 PMs asking about what was going on, no replies. Eventually I voided the shipment and traded to somebody else on here.
If I would of sent my ball, I would of been out a ball.
My rule always is now...If you do not provide a tracking number, I do not release your shipment....and it should work vise versa if I didn't provide one.