Even though dts may be enabled on receiver and player, you still HAVE to go into the movie's menus, in the Languages or audio setup, and choose the dts track. It WILL NOT automatically choose the dts track, like it does the DD track. Even after choosing the dts track in the movie's menus, wait for the movie to actually start, before deciding if dts is working or not. Most of the lead-in stuff at beginning of movie is not dts.
Good luck!