Xbox live family member account can't log in

[Kireck01]

I can log in using my main Xbox live account, bit when one of my kids tries to play using his log in on the same Xbox, he gets a log in error.  No we are not doing this simultaneously.  Is anyone else having this type of issue?  I have uninstalled it, reinstalled it, hard reset the zbox, put the game on the internal hard drive, and erased the data to try again. Anyone have any ideas?

Thanks!