TT GO 940 Live: FM transmitter not working

I have a new Tom Tom Go 940 Live. One of the reasons for buying this very delux model was the FM transmitter feature which allows the voice instructions to be heard over your car's FM radio.

I have tuned the radio to a FM frequency that is not being used (although in my area it's hard to find a place on the FM band where nothing is being transmitted), and then select the same frequency in my G0 940. When I press the done button, I am able to hear the drums and music that the 940 is sending out over the car's speakers, but I never heard the actual voice instructions. So what am I missing here?

Thanks

See this thread It may apply to your model as well.

p.s. Do you mean a 740, not 940 Live? Don't think the 940 is available in the States.

Thanks for the info. I've downloaded this mp3 file. BTW, I'm in Europe.