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.