Audio Systems: rear glass fm antenna connection, factory antenna, antenna connection

Question
I have a 2002 Isuzu Tropper, I change my factory cassete radio for a CD Player Sony radio, all the wires are connected except the antenna cable, the Sony radio accept 1 antenna cable, but I found 2 cables, one bigger thant another, I hook up the bigger one but I get no recepcion.
Where I have to connect the another cable?.
Thanks.

Answer
Some vehicles need an adaptor from the factory antenna cable to the standard antenna receptacle. Izuzus are rare here in Canada, but check with a local stereo shop. You also may have a premium level vehicle, and the power antenna wire may have to be connected not only to raise a power antenna, but to activate a separate "signal" amplifier.