how to fix my car's CD player?

hi there i have a nissan almera action r reg 1.4 petrol i have recentley changed the radio for a cd player it was straight forward job all i did was unplug and plug back in but as i tried it it didnt work i tried the old one but the same happend i have check fuses under bonnet and under steering colum and i have found out the rear window heater also dosent work no either please someone help really doin my head in please thanks

martin fletcher
September 2010