SERVO DSS-M15S DOESN'T WORK - PLEASE HELP!

We bought 2 DSS-M15S Servos because we need 270 degree turning. However both Servos don't work.
We use the simple test below, and the test works for a regular 180 degree Servo. When we do the same test on the DSS-M15S Servo, it doesn't turn at all. We can feel a slight vibration when the power is on.

#include <Servo.h>
Servo myservo;

void setup() {
myservo.attach(9);
}

void loop() {
myservo.write(0);
delay(3000);
myservo.write(30);
delay(3000);
myservo.write(60);
delay(3000);
myservo.write(90);
delay(3000);
myservo.write(120);
delay(3000);
myservo.write(150);
delay(3000);
myservo.write(180);
delay(3000);
}