OEM iPod Kit - Everything Looks Good - Song Doesn't Actually Play

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Installed the OEM iPod Kit, however the chosen song won't actually play. I set the headunit to CD2 and can skip through various CD's (albums and playlists) and tracks, and the chosen song changes on the iPod's screen - however it doesn't play. The track timer just stays at 0:00. It should play automatically, as it does in Red Valdez's video. Any ideas on what's wrong?

It's a 2005 380 LX with the 6CD Stacker, and an iPod Classic 120GB. I didn't connect the extra yellow battery cable for DIN-1 Add-Ons, and I didn't change any of the switches on the unit from the factory settings - which should, and appeared, to be all on.

The iPod has seen some shit, so one thing that occurred to me is that the iPod dock port is damaged in some way (I usually just use AUX) however it updates fine etc.

Edit: Zarbs, in an excellently detailed post, had to turn the first two switches off before it worked, will try this.

Edit 2: Didn't work : / With switch 1 and 2 off it acts exactly the same. 1 off and 2 on causes an error to display on the little screen. Changing 3 and 4 changes what songs cycle according to the iPod's screen - they JUST WON'T ACTUALLY PLAY >.<

Edit 3: It was my iPod. A quick reset and it worked instantly. *Have-you-tried-turning-it-off-and-on-again-face-plam*.