Remember that there are only so many rooms available at particular rates, whether they are discount codes, AP rates, DC rates. So maybe all the rooms at the $89 rate are gone.
We tried to use a code from Mary's site at AKL for one night in September. The CM did not have any rooms at that rate available ($174), but did find us one at $199.
I would make the ressies at $99, then just keep checking Mary's site for new discounts. You can always cancel the first ressie. But you don't want to loose out on that rate too.
Good luck.