Unable to find lzo-devel package in RHEL 6

Issue

Yum is unable to find the lzo-devel package on a system which is fully registered to the Red Hat Network and running RHEL 6. When searching for the package the below output is shown:

[root@vpn-admin0 ~]# yum search lzo
Loaded plugins: rhnplugin
================================= Matched: lzo =================================
lzo.x86_64 : Data compression library with very fast (de)compression
lzop.x86_64 : Real-time file compressor
[root@vpn-admin0 ~]# yum install lzo-devel
Loaded plugins: rhnplugin
Setting up Install Process
No package lzo-devel available.
Error: Nothing to do