hi , the distance in mission planner keep changing even i never connect sonar to APM2.6 . may i know why ? do i need a code to run the sonar MB1260 for APM2.6 ? may i know where to find the code ? 

and even i connect MB1260 to APM2.6 , the distance keep changing and is not accurate . may i know what shall i do ? please help ~ thank you ~