Problem/Bug /manuadd doesn't work...

Hello,
Recently I've been trying to add new tags and edit them on Server.pro (I have GroupManager and Essentials) Im not really sure where to ask this to be honest.. Anyway, as I worked on the tags ([Owner], [Admin], Etc.) I went to check on my server to try different codes and see how it looked, then I saw that i was moved from [Owner] to [Default] (Which i called newbie) I attempted to use /manuadd Josefina_1303 (my mc username) Owner and it said i was moved, but when i typed i was with the tag [Newbie], i attempted restarting the server and now i can't use /manuadd

I was given a error log but i don't understand it, it should be attached below and any help would be very appreciated!
Thank you
Josefina_1303

Also here are the things i modified, all i changed was the prefix and changed "Default" to "Newbie" then back to "Default" after this happened.