Rig Child of constraitn not workign correctly

Hi, for some reason my Child Of constraint on my Arm rig isnt working the way it should?

[video]https://youtu.be/jfLmG2sQ_10[/video]

i would really appreciate if u guys could help me figbure this out, its been bothering me for hours.

Thanks in advance,
lyno

Blend file please :slight_smile: