Cast on Crit missing socketed skill

Maybe a bug or not,

I have lvl 16 CoC gem which works fine with lvl 15 Comet, but when i put a lvl 16 Comet into the slot it deactivates CoC and says missing socketed skill.

I have a +4 lvl from global modifiers on comet.

Spirit is certainly not an issue.

Doesnt work with weapon set 1 or 2 or both.