sliding door problem!

my passenger side sliding door would sometimes close and sometimes it would close then re open again! it will close all the way, not latch then re open! sometimes the door will close but the buzzer will keep on sounding whenever the transmission is in drive or reverse!

sometimes a simple fix would be to, when the door is closing and when it re opens turn the switch off for the passenger sliding door the on and off switch, this will stop the door from fully opening, then turn the switch back on again and click on close! it will fully close the door! but the buzzer sound still beeps when shifted to drive or reverse on solution is to turn off the sliding door switch on the drivers controls!

what could be the culprit of the problem? please help!