hello everyone!! i bought a car with a sony cassette player XR-C2400 and CD changer CDX 601. when i put CDs in the changer a loading start then i see every thing on the screen ( you know number of CDs and tracks). the timer start also yet NO sound. what's the problem please. is it the type of format or what??!!! help me please!!!! note: the cassette and radio work very well!!