plugin help

GOOD MORNING EVERYONE (GMT+08) I need your help regarding with this "MMOCore" plugin thing, basically as you can see on the video, SKILL 3 and SKILL 6 on this "Assasin Class" is not working no matter how hard I press, the second video also show that the "ARCHER CLASS" the "Skill 4" and "Skill 6"...

Plugins Downloaded: https://black-minecraft.com/resources/mmocore-dev-build.566/update/17360/ Context: Currently I am using the latest dev builds that I have been downloaded on the site, but the thing is I don't understand why whenever I input /profile on my server it says null and this was the...