I could well be a security code problem, however no one will supply that info except the manufacturer of the car as thats the whole point of it being secure, so if this does apply you would require to supply a dealers agent with your cars VIN number to enable them to check the records, they of course charge for this! The only other option is to seek out these small usually mobile phone outlets who also advertise a radio unlocking service, as your problem is quite a common one, needless to say they also make a charge. PS: as far as the reference to the car dealer is concerned, this is assuming that the radio is a manufacturer fitted device.