Interesting results when I tried to use one of the codes with my Hhonors account. It brought up the discounted rate in the pre-reservations screen (with an asterik noting it may not be the final rate), but when I booked it, it then indicated the full rack rate without the discount.

My Hhonors profiles has my employer listed. Must be something in the software that looks at that.

By the way my company has some corporate acccounts, but not specifically with Hilton, but we use an american express rate for Hilton that is, on my company travel site, higher than the hotel rack rate.