Libsdisguise not working?

Hey guys!

so i have a little probleme that Libsdisguise is not working, so this is what i try:

ChickenNator:
Type: SKELETON
Disguise:
Type: chicken

i think that is the only thing i need to make a skeleton look like a chicken but when i put it on a spawner (/mm eggs get ChickenNator doesn't work at all) i get this

http://prntscr.com/fx6dce


and the limit of spawns are 1 but it,keeps going here

i really need this to work to keep...

Libsdisguise not working?