i have a 01 c240 and im trying to change out the radio.i have the correct harness and ive been installing radios in my cars for 13 years.this is my first merc.im trying to put in a new pioneer avh-p1400dvd radio and i had it all wired and got nothing.checked all the connections and still nothing.i hooked up the factory radio back up and it did work.so i rechecked my setup and still had nothing.i decided to try another aftermarket radio i have and still nadda.whats wrong and what do i do?

 

a 193 people have looked at my post and cant offer any help?