My server motor from the Arduino Starter kit doesn't seem to be working with the example sketches or the sketch from the book. Everything is wired correctly but there is no movement, even though the debug code is fine. So I started looking up why, it seems that it needs more voltage, so the book is wrong? I really expected everything to work in this book and this is quite frustrating.
If the servo is a 5V servo and you are delivering 5V to it and your servo is wired correctly more voltage will not help and may damage the servo.
To check if the servo is good and is wired correctly, power it on and push gently on an arm of the servo horn. You should hear the motor grinding a little as it tries to correct the displacement caused by your pressure.