JavaFX 2.0 :: Setup CellFactory Of TreeView?

I create my own TreeCell class to customize the look of the tree items of a TreeView which is displaying java.nio.file.Path information.
 
To setup the CellFactory of the TreeView I used the following:

pathTV.setCellFactory( (TreeView<Path> tv) -> {
return new MyCustomTreeCell();
} );
 
This works... Now I tried to do some other things with my custom tree cell class so I created an instance of it
 
MyCustomTreeCell mctCell = new ...

Later I changed the code to setup the CellFactory
 
pathTV.setCellFactory( (TreeView<Path> tv) -> {
            return mctCell;
        } );

This doesn't work ... I did not see anything in my TreeView...
 
Here is the MyCustomTreeCell class:

public class MyCustomTreeCell extends TreeCell<java.nio.file.Path> {
private final ImageView icon;
public MyCustomTreeCell() {
super();
icon = new ImageView();

[Code] .....