MACBOOK TO HDTV (Audio Problem)

I've connected my new Macbook to my PHILIPS HDTV (37PF7320) using the mini DVI - DVI TO HDMI cables. The video quality is perfect.

However, I'm running into problems getting the audio out of the Macbook and into the TV. According to the TV manual (information later confirmed by Philips tech support), the way to do this is to connect the laptop to the digital audio input (coax / SPDIF) on the back of the TV and then instruct the TV via the SETUP/SOURCE menu that audio for the HDMI input is coming in throught the digital audio input. I did using the following cable:
http://www.ramelectronics.net/audio-video/custom-audio-and-video-cables/rca-to-3 -5mm-s-pdif-cables/custom-series-spdif-cable-digital-audio-3-5mm-to-rca-spidf/pr odSPDIF.html
However, I don't get any sound at all. I tried connecting my DVD player to the digital audio input in TV to make sure it's working and it works perfectly.

I don't know what else to do. I'm thinking that perhaps the optical digital output from the Macbook is not compatible with the coaxial digital input (S/PDIF) in the TV. Does anybody know if that is the case?

Can anybody offer a solution?

Thank in advance,

curuxu