CDP M26- no sound?

I've bought a (car boot, for the record player) XO D501 system with this CD attached. Everything else (phono, tuner, tape) which are the integral units work perfectly and all the buttons on the CD system work but there's no sound. Am I plugged up wrongly? dodgy connections? a missing lead, although I can't see any vacant ports.

Thankyou to anyone who can help