I set the cmd to the npc and when I click the npc it just gives the "Unknown command. Type "/help" for help. Ive tried with very simple commands like /msg, /say, /tp, /help and nothing works. The latest version doesnt work with 1.8

Can you list all of the plugins that are on your server? Currently you are the only one having this issue. Are you running spigot or craftbukkit?