how can i fix starting prob on my 2000 3 series 330 diesl auto tourer?

have had problem starting my bmw for the past 2 or 3 weeks sometimes it starts no problem other times i just can't get it to go the problem seems to be the key fob or its recignition to the car , the key fob unlocks and locks the car fine but more often than not will not start it when trying to start with the key in the ignition it will only activate the radio and the mileomiter section of the dash there are no warning lights on the dash and the heater and fan do not work sometimes it can take 20 to 30 atempts to get the car to start any ideas ?