Problema minecraft server: YOU DON'T HAVE FML INSTALLED, YOU Can't CONNECT TO THIS SERVER?

Aiuto! Ho fatto il server per la 1.6.4 e ho inserito la pixelmon pero quando entro mi dice YOU DON'T HAVE FML INSTALLED, YOU Can't CONNECT TO THIS SERVER come faccio?

Guest

First of all, did you buy minecraft? If you bought minecraft, it should work, but if you didn't buy minecraft, you can only go on cracked servers. Are you talking about realms, if so then i don't know.

Elvis