Android Bluetooth joystick

Hello Kas,
I'm glad I found your software because of its user friendliness. However I have a small issue. I tried connecting a servo motor to it and added the following code:

HorizontalServoPosition = map(joyX, -99, 99, ServoH_Min , ServoH_Max);
HorizontalServo.write(HorizontalServoPosition);

The servo does what it is supposed to do but it flickers continuously. Meaning it moves a little and comes back. Can you please suggest me a remedy?