It is important that when the servo arm is in the 'down' position that it *just* pushes the shutter button.  Any more travel and it will strip a gear or peel itself off the camera.  To get the throw right, mount everything on the camera *minus* the servo arm, and toggle your gear switch 'down'.  Carefully put the servo arm back on the servo with the arm as low as you can get it, either lightly touching the camera shutter button or just above it.  Next toggle your gear switch 'up', remove the servo arm and rotate it one 'notch' down and reinstall.  Your arm is now very close to being right, so now you'll go into your radio's setup to the EPA  for your gear channel.   Now working quickly, toggle your gear switch 'down' and listen to see if you are binding your servo.  If so, quickly reduce the end-point for the servo until you stop hearing the servo grind.  Hopefully it is still fully pressing the shutter at this point.  If not, then increase the EPA until the shutter is reliably being triggered.  A small amount of grinding should be ok, but obviously don't leave the gear switch  down for long periods.