Hi delbob_1,

Not sure on this one, but I suspect that iPods don't conform to the same standards as a generic USB stick type mp3 player (which I'm guessing is why some Sony stereos have a specific iPod connection as well as a normal USB connection), and this is why nothing is happening.  Certainly the compatibility guide on Sony's website for the GT450 makes no mention of any iPod models.

My suggestion would be to use the good old fashioned 3.5mm jack input on the GT450 via the headphone output of your iPod.

hope this helps.