[CentOS] Why no upgrade?

Fri May 18 02:56:40 UTC 2007
Scott Moseman <scmoseman at gmail.com>

I have 2 installs of 4.4 that I'm experimenting with.
'yum update' on one of them upgraded to 4.5, but
the other system does NOT upgrade.  Any ideas?
I ran a 'yum clean all' but it did not appear to help.

Thanks,
Scott