Connect PS3 to Home Theater System?

[Iijklj]

I just bought a 50" Samsung Plasma TV and a Sony Home Theater System. I have an HDMI cord running from the tv to to cable box, HDMI cord from home theater system to tv, HDMI cord from PS3 to tv, and optical sound output from home theater system to tv. I can watch tv and use the home theater system, but when I turn on my PS3 there is no sound. DO I have it connected wrong or do I have to change a setting on the PS3? Help would be greatly appreciated. Thanks

[Yoda]

Go into the ps3s internal menus and select the option that includes the hdmi