We are having problems mating a Philips Radio Cassette to a Phillips CD Cha?

The car is a 1998 Citroen Xsara, which is fitted with the Philips Radio/Cassette model 22RC 465/35S. I have purchased on E Bay a CD Changer(s) RC026/50 & RC026/50B. Both couple through the 8 pin blue square plug. However, when the band change button is depressed and the eject button on the changer nothing happens. The changer makes a sound as if it is going to eject, but the cartridge does not come out.
Can anyone advise me or perhaps have a manual I could purchase or refer to.
I am at my wits end on this. The car had a Sony unit fitted, which decided to operate very slowly & with little or no volume. I had hoped that the corresponding Philips unit would overcome the problem.