NPC Problem in server

Okay so my server is using cakescriptg2 and im making a zombie survival/ rp thing. So the map im using is zs_thecity which has zombies already spawned. So i get on the server and go to the zombies and when they try to act me no damage happens it just looks like theyre hitting air. I checked to see if god mode was on which it wasnt and i also enabled pvp damage. Also the zombies make no noise so how could i fix all of this?