We received a brochure from your lovely Grande Lakes property today in the mail. The rate code provided contains four characters and the rate code space online provides for only three characters. WHY? We have experienced this same problem in the past. Why do I have to call the reservations center to book this visit? Thank you!
If you log into the marriott.com site and go to the hotel page and check the 'Deals at this property' the promotion should be there for you. If not, just drop one of the letters (probably the first or last) and see if the code works.