Ipod connected to 930T - no sound

[mug]

I have a 930T with a genuine TT Ipod cable connected to my Nano. I have only had it a few days and at first, it definitely worked. Now I can not get any sound out although it connects and looks like it is playing on the930T screen. I have checked everything I can think of and to eliminate one variable have switched the speaker preference to the internal speaker instead of the FM transmitter. I still get normal navigation instructions played. Also, have just discovered that it will happily play MP3's from its internal drive. Any ideas much appreciated.
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TT 930T and Traffic subscription
.....has replaced my.......
PDA: iPAQ 5550
Application: TT 5.17 with Traffic
GPS: TT bt gps in TT hard wired cradle
PDA Mount: Silver Shield Amplified Speaker Mount & Cradle.

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