Yum problem? Can’t update anything?

Hi!
On one of my node I am having a problem with Yum, it's not updating at all – and I can't figure out why? I've disabled iptables and yet still doing want to do anything?

Code (Text):

[root@spanky ~]# yum update

Loaded plugins: fastestmirror, security

Determining fastest mirrors

YumRepo Error: All mirror URLs are not using ftp, http[s] or file.

Eg. $releasever is not a valid release or hasnt been released yet/

removing mirrorlist with no valid mirrors:…

Yum problem? Can't update anything?

See original post by obay