Bugged Thread - Delete Please

The error "You did not select a valid group to move this user to." I have found to be lurking on my forum, more specifically on my modcp, my mods can not ban anyone everytime they put someones name and reason and time this error will come up: http://i.imgur.com/qFWynAF.png
My banned users id is default (7)
I am using 1.8
I am using 1.8 / 1.6 Theme Majestic Dark Mybb
File verification returns no errors.
Plugins: http://i.imgur.com/RUgjP7l.png | http://i.imgur.com/ynuWATn.png

Edit1:
Looking into modcp files the error is named "error_nobangroup" but I dont know how to fix.


Edit2:
Banning still works on my admin panel, still no luck on mod panel.