I recently got this AND UA-767 from my uncle's house who passed away. It appears to have all the juice it needs and it appears to be working but it never actually shows a reading. Can you tell me what I might be doing wrong or if there is a fix to it? Should I just throw it away? I put new batteries in it and goes all the way up to about 180 or 150 depending on which setting I use and then it declines all the way to 0 but never actually displays a blood pressure reading.