hi make sure you have the correct code obviously. then make sure you are using the correct sequence of buttons. like on mine you hold down "rds" and "fm2" buttons together until the radio flashes 1000. then you enter the code by using the radio presets. number 1 enters the first number according to how many times you press it(6 times enters the number 6) then use preset two for the second number and so on. then I have to hold down "rds" and fm2" together again and the radio once again displays safe, but then goes to a frequency. make sure you have the right code, then look in the sound system manual for the correct sequence.