No Sound from Mac to LCD with RCA cable

Hello,

I have a MacBook Pro 2009 and I tried connecting it to my new 42 inch LCD TV using an RCA cable and no sound would come out of it. I also tried it simultaneously whilst connecting the computer with an HDMI cable, using a Mini Display Port adapter. Neither did it work. Does any one please have any suggestions, its very annoying!

Many many thanks in advance!