I am now also able to check-in online now that my redress number is finally working.

I also figured out that Amex Travel does NOT send my redress number and may be sending other information incorrectly (including always messing up my Avis reservations), so every time I book a flight I have to call up US Airways and have them manually add in the information and my redress number and then call Avis and re-book the reservation correctly.

But SOOOO glad I can check-in online (and via my mobile too!)