Well, yesterday I got it all to work!
I logged into Emerald Club.
In the Promo Code box I entered NHOL
In the Contract ID box I entered the old Disney Club code (you can find this on my site)
In the Coupon ID box I entered the Disney Club coupon code
Voila, it all worked fine. So now I have an Emerald Aisle reservation with all three discounts.
For my October 12-16 rental (4 days), the rate I got for a full-size was a little less than $110, all taxes and fees included. This is less than half the rate I originally received, when I booked back in August.
Mind you, I had tried to do this at least a dozen times in the past, and it didn't work. I have found that National's web site is extremely quirky and inconsistent.
If you are having trouble making this work, one thing that seems to help is to clear out old cache files, temporary Internet files, and cookies before going to the National web site.
Also, as a previous poster mentioned, the codes are always subject to capacity controls. I can only advise that you keep on trying... it worked for me.
Mary
MouseSavers.com