By through, do you mean when you use the AMEX landing page to click through to the Hilton site? I am in Australia but have recently had a similar issue. Nowhere in the terms & conditions does it say that I would not earn points. The first time I did as above, I booked one room and was credited a stay and points using the AMEX rate and booking on the Hilton site. The second time (booked two rooms) I did not. I followed this up with Hilton and the first response was that I booked through a third party and not the Hilton site. They credit me with 2,000 points as a courtesy. This answer was not quite good enough, so I wrote again and they agreed this time that I did indeed book through the Hilton site but still said I was not eligible for points (no reason was given) but credited me another 3,000 points anyway. This is still less than the 6,500 I received for one room on my previous stay using this promo. I am still a bit annoyed at this as I had a few more visits planned to this property before the promo expires. I also note that other Australians have not had this problem so it may be bad luck for some such as for the OP and me.