Iphone 4 won't load into the MMI via the red cable

Hey Guys.

Searched around for 20-25 min on the interwebs and here, but coulden't seem to find a solution.

Ios is 6.1.3

Phone is a Iphone 4 32GB phone.

The issue is that i normally use a SG4 for my everyday phone usage and an Iphone 4 (with no sim) as my media player (worked as a charm on my old 8p model with a Alpine headunit)

My goal was to always have my Iphone connected via the cable and connect my normal phone via bluetooth for calling etc.

The music will play over the bluetooth, but I can't select songs etc. When I plug it in the MMI says "loading device" and after 30sec-2min it cuts of saying "media unreadble" (or something similar)

I'm pretty confused to say the least, seeing it actually loaded the phone this morning, it could see everything, but when I selected a song, nothing happened.

Is there anyone out there with a set of smarty panths on ?

Cause I'am just about all out of possible solutions.

I know a SD card is a possibility, but I would like this solution more, since it's easier to update my song list via Itunes, then manually doing it via "drag and drop" etc.

Help is needed and every possible solution will be tried!

Thanks in advance!

Update!:

Went to the dealer, he checked it said he had seen it before but it's fairly easy to solve

1) remove cable (entirely) while the car is on
2) shut down your car with the cable still out
3) restart your phone
4) start your engine and plug in the cable
5) connect phone
6) enjoy your music, playlists etc.
7) be a happy camper!

Worked for me, so i'm well happy