I went to change the battery in my fathers range finder, with a new 9 volt Duracell battery. When I did,it didn't work. I tryed another and it didn't work. I put the old battery in and it worked, thats when I noticed the battery that came with the rangefinder from Leica, has a blue bottom and the ones I bought at Kmart have black bottoms. Is there a difference in 9-volt batteries? They were bothe alkaline batteries.... Need your help..