Get problem when control servo RC by potentiometer

Hey guys!
Im working a robot arm control by potentiometers
I write the code in arduino like that : myservo.write(map(value,0,1023,0,180)); When the potentiometer at 0 position( analog=0), the servo vibrates. After i rotate potentiometer until the value= 80, the servo is stop vibrating and moving 
Can you give me some suggestion to solve the problem  

Sincerely thanks!

Servo Range

Servos don’t necessarily traverse a full 180  degrees,

Find out where the limits are and don’t go there!

https://www.arduino.cc/en/Reference/Constrain