Attempting to attach a subscription to a Unit/System

Hello all.  New user to Red Hat here, so if I'm asking a stupid newbie question, I apologize in advance.

I'm attempting to pair my subscription, a Red Hat Enterprise Linux Developer Suite, with a virtual machine I've setup (6.3 64-bit).  When I attempt to associate my subscription with this machine, I get the following error message:

org.candlepin.util.CertificateSizeException: Too many content sets for certificate Red Hat Enterprise Linux Developer Suite. A newer client may be available to address this problem. See kbase https://access.redhat.com/knowledge/node/129003 for more inform

I select my system, attach a subscription (choosing one of my 100 of System: Virtual) and when I click 'Attach Selected' I get the above message.  I didn't cut off the word 'information' - that's how the error displays on my screen in red text with a pink background.

Can anyone point me in the right direction of what I'm doing wrong?

Also, if this is easier, feel free to point me in the direction of how I should go from the point of installing Red Hat in a VMware environment (Minimal Install, so no GUI on it) to the registration process to activating it so I can get access to the yum repositories.  I've tried looking for a FAQ, but I can't seem to find any kind of a step-by-step for how to do this.

My end goal:  To be able to install, uninstall, rebuild, and work with Red Hat servers in a test environment so I don't touch my productions systems and have a test bed for learning, eventually working towards my Red Hat Certification ideally.

Thanks in advance,
Charles