There are a few threads on the forum, but first how far did you go with the booking ? need to select a room first .... and some hotels don't do the redemption on certain rates. Also check that you actually have the points available .....

Example of initial search, and then when you select a room, it shows you can pay with reward points
( Very nice hotel btw )


Rates showin , but no points


When you click to select the room, it offers points as a payment option.