towzer

Hi First post on this forum. My daughter has bought a C2 on 57 plates from and auction. When we picked it up the araiel was missing, tried with a CD and the unit worked perfectly so thought all was ok. She subsequently bought a screw in type areal from Halfords ,but still can not pick up an station on any frequency. Does the araiel need to be from a Citreaon main dealer ( which I struggle to think is correct, but prepared to be educated on this) or does any body have any ideas what the problem could be. Thanks