Hilton HHonors - Anyone tried to Doubletree OMXD promotion?

Sorry if this has been posted. With search out, I couldn't find it.

This promotion gives double points and miles at participating midwest DT.

http://www.doubletreepromo.com/

However, when I enter the promotion code, I just get the normal rates. I don't get any kind of message telling me the OMXD rate is or isn't available.

Has anyone had a stay using this code? Did it work?

Thanks.