WHY does the Robot stop via Safety Stop?

Good morning,

I´m don´t get why my robot stops via Safety stop.

I´m checking at a script for the actual force value.
If that value is more then 80N it should move the Robot back…

Sometimes its working fine, but now the Robot will tell me it went up to 120N and it stopped via Safety Stop…

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I don´t understand it… and it´s quite frustrating to not understand why the robot is not reacting…