Nagios xi installation problem by fullinstall script

Hi Guys,

i need one help for installing nagios xi on RHEL 6 system.
I tried to install nagios xi 2012 & 2011 both version on this server but i am getting one error in the install.log as below

Configuring Yum…
ERROR: unable to read system id.
Your Red Hat Installation is not registered or does not have proper entitlements.
Please register or enable entitlements at

Can anyone help me what should i do for this.