hi, my grandson,s corsa,1.2.sxi 51. plate.c/lock prob?

all the car locks off the remote, an key, only when unlocking, with remote key or else. his nearside pas,door (2 door car) will lock with the rest, but wont unlock , he has to reach over to raise the button up. any idears anyone, i can earn some browny points for this, "he,s my favorite grand boy really. cheers all out there. and thanks . OLD DAVEY.