No sound through HDMI cable gateway laptop

Hello,

I have a Gateway M1631u Laptop that is HDMI ready. When i went to hook everything up the Video came out perfect but there was no sound through my tv.

Is ot possible that my laptop doesnt support sound through HDMI? IF so is there somehing i can do about it? (like download a program to trick my laptop)

I read the other forums in my sound panel it has Digital Audio (HDMI) but it is grayed out and says "not plugged in."
My speakers is sigma high def audio codec which is where the sound is play through now.
I also have a Digital Output Device (SPDIF out) when i make that defualt nothing happens.

SO i could use any help if possible.