Doorbell missing activity

Hi, We installed a new doorbell over Xmas and have been tweaking it to try and get the best recording without it going off all the time. The problem we have is it's a busy path so dog walkers set it off all day so I made a mask to try and hide this which may be the issue. I park my bus on the drive which it missed today, it just appeared but it's defonnit hidden by the mask... Also we have milk delivered on a night who come right up to the door which never gets records. I've put the sensitivity all the way up ( and everywhere in-between) but it's not doing its job. Is it broken or just not a bit pants? Ps.. it's on battery if that makes any difference.