Vistacam 1100 operation.

I have just installed a Vistacam 1100 above my front door. No problem with the installation and pairing. However it keeps operating seemingly at random. I have a touchscreen deadbolt on the door so I know who/when someone is entering or leaving but the camera doesn’t always pick them up, yet I get video clips of non events? Also can you obtain clips longer than 10 seconds? Any advice would be much appreciated.