NHL 12 for XBOX 360 problem

[Mr. Brass Bonanza]

We have had Wii for years and my son loves to create hockey teams and players for NHL2K11. But every once in a while, his teams and players disappear...they just weren't there anymore and we never figurered out why.

For Christmas, the kids got XBOX 360, and my son has been doing the same thing with NHL 12...creating teams and players...and the SAME THING is happening. It's a different game system and a different game, but his creations are still disappearing every now and then. :(

Does anyone have an idea why? :confused:

Thanks!