Celtic Heroes

I got this crystal ring of poison weap. My poison initially adds 34 poison dmg, and was 20/20. But after I equipped the ring and raised it to 22/20, it still displays that it adds 34 poison damage. Is it some sort of display problem? Or it's a skill bug?

Skill is upgraded, it just doesn't show on description, cast poison wep and count how much dmg it adds