How many Management subscriptions for Red Hat Developers Suite?

Hi,

I can't find any documentation listing a limit for the number of systems that can be Managed under a single Red Hat Developers Suite. However I can only seem to register up to 3 systems before I get errors, even though when I go to https://rhn.redhat.com/rhn/systems/SystemEntitlements.do I see:

Entitlement Counts
Base Entitlements
Update: 0 systems entitled, 1502 available entitlements (1502 total)
Management: 3 systems entitled, 498 available entitlements (501 total)

That screen seems to imply I should be able to register more systems, but I can't seem to. I have to delete one before I can register another.

I am using rhn_register.

This is a problem for me because I am working with a multi-tier system involving VMs, so I could really use some more Management entitlements.

Am I doing something wrong?

Thanks,
Bob