not to sure mate may just need re-programing but ive lost one of mine and just been qouted £150 for a new one from the stealers so hope you get it sorted via a new program etc which is around £30 so am told anyway matey 
Does amaze me the amount they charge. My brother-in-law has the gear for reprogramming merc keys. Due to the business he is in, he has to sort out a lot of truck units. Apparently it takes seconds to do.