The position of node is wrong when node has a layer not be the last layer

[natee]

When a node has a 'layer' and it doesn't have a target node,the position will automatic move to the last layer . Actually, if I set a 'layer',why it didn't display belong to the layer?

The reason why I need to do this is that when I add some labels for each column(layer),the position all goes mess.

sankey data:

{"nodes":[{"layer":0,"name":"L0S0"},{"layer":0,"name":"L0S1"},{"layer":1,"name":"L1S2"},{"layer":1,"name":"L1S3"},{"layer":1,"name":"L1S4"},{"layer":2,"name":"L2S5"},{"layer":2,"name":"L2S6"},{"layer":3,"name":"L3S7"},{"layer":3,"name":"L3S8"}],"links":[{"source":0,"target":2,"value":3},{"source":4,"target":7,"value":1},{"source":0,"target":3,"value":1},{"source":1,"target":4,"value":4},{"source":2,"target":6,"value":2},{"source":4,"target":5,"value":2},{"source":2,"target":8,"value":1}]}

Here is default display: http://output.jsbin.com/huvujefezo/2 , the layer 2 and layer 1 moved to layer 3 position.

So I chaned the source code,like this:

function scaleNodeBreadths(kx) {
        nodes.forEach(function(node) {
            if(node.layer){
                node.x = node.layer
            }
            node.x *= kx;

        });
    }

After this,the chart display as what I want.
http://output.jsbin.com/kisuwi