Some questions regarding a servo motor's data sheet.

[selbstdual]

For a better understanding, I uploaded a video: Here: http://rapidshare.com/files/112603057/c.avi.html which is 2 minutes long. You will need the xvid codec aswell as a mp3-codec. You should see that the part moving is almost parallel to the cam when being in position X. In software I tell the program to make the servo turn back to the old position as mentioned. But it doesn't as you can see.

And I would like you to tell me why.

EDIT: OR here if you prefer some service like youtube: http://www.revver.com/video/863645/problem-with-servo/