RT3 no cd-changer option available in source

[Peugeot207GT]

Hello, i have a 2007- Peugeot 207 with a CAN-based RT3 system with a 5 disc blaupunkt cd-changer, the software version is 6.62. When i press source i cant select the cd changer, i can only choose between aux and radio. however, when i start the car the cd changer is the default source and it stays in cd changer mode for 10-15 seconds. I do not have any cd's in the changer.

I have also bought a Yatour Digital CD Changer https://www.ebay.com/itm/263818067355. And when i disconnect the blaupunkt cd changer and connect the yatour i have the same problem. I want to replace the factory cd changer with the yatour device, but i cant get it to work. Does the factory cd changer require cd's to be able to select it when i press source? if so, why does the the yatour cd changer have the same problem?
Does anybody have an advice on how to proceed with the troubleshooting?

[GiveMeABreak]

Be aware that the some CD changers are system-specific and must be the correct electrical architecture to work with the head unit, which is why the various CD changers that PSA used back then couldn't be interchanged.

This may have something to do with it. The Yatour will only use the CD part of the Quad block connection to mimic the CD changer, which is why you have to organise your music files as if it was a CD changer - into 6 folders.

I can't advise you on the Yatour, because as far as I know these were only used on later RD4 systems, so may not be compatible for that reason.

Is the physical CD changer the original one that came with the vehicle? Because if it has been replaced with the incorrect part at some time, that may be the reason why it is not working.