The Mégane II Owners' Club

First time on the site and it has given me some useful information but!
I have a 1.5 dci Dynamic '57 plate and so no 6 disc CD player.
I purchased a second hand player which apparently was all working. I fitted it into the car with the lead to connect it to the radio, put the code in and there was life!
I put the radio and CD player back into the dash and then tried to insert a CD but it just would not let me put it in. It comes up Error CD but it just won't let me put a CD in.
I disconnected it all and then reconnected it, just to make sure all was correct
Still no good
Any ideas or suggestions?

Is it the single slot multi CD or the type where you load a 'cassette' with the CDs?

I have the 175dCi Lux with the 6 Cd Changer and I get "Error CD" when I put an MP3 CD in.....weirdly because the stupid thing doesn't play MP3s, even though the single slot CD player installed above it does!!
There isn't a disc stuck in it is there, although I would have thought it would spit it out if there was(?).

I've seen the error cd message on mine, it held onto that cd for months before spitting it out, maybe there is one in already.