potential issues include:
*antenna booster wire: labelled as 'AUT ANT' wire on the schematic atop the original headunit, and is wire #5 in the power-ISO plug; should be the BLUE wire (no stripe) on the sony headunit that connects up (confirm in owner's manual)
*antenna lead: is it connected up to the new headunit?!
*tuner settings: first ensure the tuner mode is set to 'DX' (distance) in case the stations are a weak signal; 'LX' (local) only picks up strong signals, DX picks up weaker ones too
