All the tekkit items are gone after copying the world

[afwas3]

So i was running a tekkit server on my laptop and me and a couple of build a lot of stuff.

But then i wanted to host the server from my other computer so i got a server running and put a copy of the tekkit world in the right folder but when i logged on, the world was there and also the players position was correct BUT all the tekkit stuff was gone. The quarries, the engines, te machines, everything... The normal vanilla minecraft stuff however was still there. All my chests, workbenches etc. but even in my chests all the tekkit items were gone.

I have tekkit installed and running correctly and if i try to make a tekkit item (i tried a landmark) it works.

What am i doing wrong

[afwas3]

I forgot to add that i transfered the server from a mac to a pc