Unable to register Linux Server

Hi,

I am trying to register Rhel 6.5 x86_64 (evaluation) which is installed on a vm within vSphere with a static ip. I can ping any host within and outside the network successfully. But when I am trying to register in command line (as explained here https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/5/html/Deployment_Guide/registering-cmd.html) I am getting the error message:

$subscription-manager register
$Username: username
$Password: password
Network error, unable to connect to server.

But when I ping 209.132.183.181 (redhat.com) the ping is working just fine.

I installed the same RHEL Server on my local machine where DHCP is configured and I can register.