cannot get block's tile entity

hey everyone.

I'm currently working on a mod, and in my block's onblockbreak class, I'm running this code:

        if (world.getBlockTileEntity(x, y, z) == null) {
            System.out.println("tile entity = null");
            return;
        }

and everytime I test it, it'll say that tile entity = null.

my block class is extending BlockContainer, I've got the BlockContainer.createNewTileEntity() overridden, with creating a new tile entity of mine, and I have registered the tile entity like so:

GameRegistry.registerTileEntity(TileEntityTPPeripheral.class, tileentityname);

If i'm missing something here please tell me what, I'm a bit lost now.