This is a mistake with the Dutch translation.
https://steamuserimages-a.akamaihd.n...5A9B3BE89B72B/
The mission basicly says that you have to kill your targets from within 100m. It is meant to say that you have to eliminate them from atleast 100m distance. I failed the challenge 3 times in a row before checking the English version of the challenge and realising this minor, yet annoying mistake.
The mission should actually say something along the lines of:
''Ga op het niveau Extreem naar Tabacal Charlie en schakel alleen vijanden uit vanaf meer dan 100 m afstand om de missie ''Van binnenuit'' te voltooien zonder dood te gaan.''
Thank you for letting me know! I will report this issue so that the wording can be changed.