Hi all I have a 520 d m sport on a 06 plate I believe this is the pre-facelift model

The issue I have is I have to be right close to the car to lock or unlock whereas as I also have a 118d sport on a 54 plate 2005 and I can be about 5-7 metres away from the car to make it work

I'm just wondering what can the issue be and if anyone else is coming across the same issues