Cannot use vanilla world in my server

[havok28]

So, I recently had my first try at making a modded minecraft server, and figured I'd give technic a go. I've already made a few vanilla servers, so I sorta knew what I was doing. Anyway, after hours of optimization and changing settings, I finally got the server to work with The Classic Pack, but I could not use one of my worlds from my vanilla server. Transferred the files like I was supposed to, but it still didn't work, can anyone help with this?

[JaariAtmc]

Why, however, would you want to use a vanilla world? You would lack so many required resources?

Besides that, log.