DnD Custom CellTable not working

[Will Davis]

I do apologize in advance if my question has already been answered or if I am just making a dumb mistake. However, I have been using this plugin for a while and have thoroughly enjoyed its use so if someone knows what I am doing wrong, I would be most grateful for a solution. 

So here is the background, I have created a cell table that has a custom AbstractCellTableBuilder provided. I'm not sure if this may interfere with the DnD. I do this because I have created my own table tree implementation. I provide the root level of data with setRowData(...) and my table builder can then create the children and such. Now I have one column that I want the user to be able do grab-drag-drop in order to move the rows around. Here is the relevant code, I have tried to leave out anything that isn't.

I create the column for use in the  buildRowImpl(...) method of the table builder

column= new DragAndDropColumn<Code, ImageResource>(new ImageResourceCell()) {
    @Override
    public ImageResource getValue(Code object) {
        return GeneralIcons.INSTANCE.twoLines12h();
    }
};

// initialize drag
DraggableOptions draggableOptions = column.getDraggableOptions();
draggableOptions.setHelper($(Templates.INSTANCE.outerHelper().asString()));
draggableOptions.setOpacity((float) 0.8);
draggableOptions.setCursor(Cursor.MOVE);
draggableOptions.setRevert(RevertOption.ON_INVALID_DROP);
draggableOptions.setCancel("select");

draggableOptions.setOnDragStop(new DragFunction() {
    @Override
    public void f(DragContext context) {
        placeHolder.remove();
        oldEl = null;
    }
});

//Initialize drop
DroppableOptions droppableOptions = column.getDroppableOptions();

droppableOptions.setAccept(new AcceptFunction() {
    @Override
    public boolean acceptDrop(DragAndDropContext context) {
        return true;
    }
});

droppableOptions.setOnDrop(new DroppableFunction() {
    @Override
    public void f(DragAndDropContext context) {
        onDrop(context);
    }
    
});

droppableOptions.setOnOver(new DroppableFunction() {
    @Override
    public void f(DragAndDropContext context) {
        Element el = context.getDroppable();
        
        if (oldEl != null && oldEl.equals(el))
        return;
        else
        oldEl = el;
        
        if (el != null)
        placeHolder.insertBefore(el.getParentElement().getParentElement());
    }
});
droppableOptions.setTolerance(DroppableTolerance.POINTER);

Then in the buildRowImpl(..) method I add the cell to the table with the column like this

TableCellBuilder td = row.startTD();
renderCell(td, createContext(2), column, rowValue);
td.endTD();

And I add the drag handlers to the table, but it is never firing. Am I forgetting to do something?

cellTable.addDragStartHandler(new DragStartEventHandler() {
    @Override
    public void onDragStart(DragStartEvent event) {
        handleOnDragStart(event);
    }
});

If you need any more information please let me know. I have used the Dnd cell table before like in the example, but never with a custom table builder, so I am not sure if that affects the DnD behavior.

Much Thanks,

Will