I created a TileEntity but after leaving the world and rejoining no data is saved. That's the class:

	private String entityID = "";
	private String helmetID = "";
	private String chestplateID = "";
	private String leggingsID = "";
	private String bootsID = "";
	private String weaponID = "";
	
	@Override
	public NBTTagCompound writeToNBT(NBTTagCompound compound) {
		super.writeToNBT(compound);
		compound.setString("id", entityID);
		compound.setString("helm", helmetID);
		compound.setString("chest", chestplateID);
		compound.setString("legs", leggingsID);
		compound.setString("feet", bootsID);
		compound.setString("weapon", weaponID);
		return compound;
	}
	
	@Override
	public void readFromNBT(NBTTagCompound compound) {
		super.readFromNBT(compound);
		this.entityID = compound.getString("id");
		this.helmetID = compound.getString("helm");
		this.chestplateID = compound.getString("chest");
		this.leggingsID = compound.getString("legs");
		this.bootsID = compound.getString("feet");
		this.weaponID = compound.getString("weapon");
	}
	
	@Override
	public void onLoad() {
		System.out.println(this.entityID);
	}

When the tile entity is loaded it should print the saved entityID but it always prints an empty string. What am i missing?

I changed the keys and now it's working.