Audio Systems: Car radio install, inline fuse, citroen saxo

Question
I got a new radio (belson BS-11500 MP3) for my Citroen saxo (97). The problem is that wen i turn of the ignition te radio just looses all memorized stations. I just pluged the original connection box of the saxo with de radio connection box. It works fine. the only problem is the memory loss when i turn off ignition.
The radio box has 4 wires and the radio box only 3. Help!

PS- My old radio came with the car from factory.

(sorry about my bad english, i´m from portugal)

Answer
Lago,

 no problem , ok it sounds like the problem is your 12 volt constant wire usually yellow , find this on your new unit , and double check the wiring, if still nothing , just run a wire directly from your battery through an inline fuse *20-30 AMP* and to the 12 volt constant wire on the units harness .. this should fix your problem .. hope this helps you out i fyou need anything else let me know

thanks