Apple ID not recognized then recognized and prohibited from registering
I have a problem signing in to Apple Support Communities with my 'real' Apple ID. When I try to sign in with the ID (it's an email address at mac.com), I am prompted to re-enter the password. I do so and see a screen that prompts me for a Suuport Communities user name, has a checkbox for agreeing to the terms for joining, and a button to continue.
When I do that, I am told that that email address is already registered (as I thought it was) and that I can't re-register this.
(Note: I was able to join using an alternate email address (my gmail address), but I would rather consolidate all my activities with Apple under one Apple ID.
How do I get this situation resolved and enable my .mac.com AppleID to participate in Apple Support Communities?