The hat mod works great on single player but as soon as I try and use it on my server everything works except there are no hats on any mobs at all, I do have it set on option 4 and have it at 100%

abd none of the mobs in the worlds have hats on either

Can you post the log for your server?

Also make sure that the mod was installed from the start. Only new mobs spawning will get hats. Pre existing mobs won't be getting hats (I think)

i no longer have logs as i ended up changing too new server (due too host issues) and upon changing the mod worked fine