There are 3 possible causes of this error:
1. You pirated the game.
2. You haven't patched JKA to v1.01.
3. You're running a different/improperly installed version of OJP vs whatever is on that server.
---Jedi Guardian of the Newbie Questions
---Masters of the Force Team Leader / Creator
---Open Jedi Project Lead Moderator / Co-Founder