Did you add the behavior file in using visual studio? And is it located the currect position (wserver/logic/db). Did you open a behavior file outside visual studio, and made your code in there? If so add it using visual studio. As it sees to me, the file is not being compiled with the other behaviors, try adding in your behavior in a working behavior file. also i saw something that was not there in your behavior file. idk if it does anything tho Code: You see the _AncientMage = () => Behav()? Change that to: private _AncientMage = () => Behav() rebuild and test.