I have a bluray that i'm trying to use on my ps3 and it does Dolby TrueHD 5.1 sound but it's not working, it says audio format not supported so it goes to dolby digital 2.0, but dolby digital 5.1 always works with other blurays or ps3 games on my speaker system so how do i get it to play in 5.1 for this dvd as well? if it helps the bluray i am playing is this:

http://www.blu-ray.com/movies/movies.php?id=1281

Thank you!