Citroen Berlingo radio shows ERROR?

Hay 88, thank you for the code for the Phillips radio, it is the number written in felt tip on the radio. However, I am still having the same problem entering the code. I leave the power on until the display shows CODE, briefly, then -- -- -- --, I put in the code using the preset buttons, then pressed 5 (as previously advised) to end the process, but it goes to ERROR (now 10 ERROR) What an I doing wrong?

Thank you.

Sheridan
October 2010