<subscription-manager register> fails, only returns ' '

I am trying to evaluate RHEL 7.2 and its virtualization (4.0) offerings. Following the instructions here https://access.redhat.com/products/red-hat-virtualization#getstarted I am supposed to install rhevm using yum. Obviously that requires being subscribed so yum has access to the RHEL repositories.

When I go to register my system to my account, I get the following output:

[root@localhost ~]# subscription-manager register
Registering to: subscription.rhn.redhat.com:443/subscription
Username:
Password:
''

For username, I have attempted to use two different usernames, one with active subscritions and one with eval subscriptions. Both output the same single quotes ('').

Any further attempt to attach subscriptions results in an error stating that the system isn't registered.

There does not seem to be any messages in /var/log/messages

Any suggestions would be helpful.