[1.7.10] Access to Nether on dedicated Server

Hello together,

I'm trying to access a tile Entity in the Nether from the overworld. I use

nether = MinecraftServer.getServer().worldServerForDimension(-1);

So that I can then use

world.getTileEntity(x,y,z);

This works perfectly fine in single player, but it fails with a crash in multiplayer. The client crashes at net.minecraftforge.common.DimensionManager.initDimension(DimensionManager.java:230) with the Exception

Quote

Description: Ticking block entity

java.lang.RuntimeException: Cannot Hotload Dim: Overworld is not Loaded!

I've been trying to figure out how to properly access the Nether for the whole day now, but can't seem to find my way around. I hope someone can point me into the right direction.