Tree attached toolbar action doesn't work, but new toolbar works well

                var treeAction = function(id) {
                treeToolbar = docLayout.cells("a").attachToolbar({
                    icons_path: "images/",
                    json: [
                        { id: "expand", type: "button", text: "Expand", img: "ExpandAll.png", action: 'treeAction' },
                        { id: "collapse", type: "button",  text: "Collapse", img: "CollapseAll.png", action: 'treeAction' }

Pleas,e check the following snippet with your own code:
it works well.
If the problem still occurs for you please ,provide a complete demo or a demo link, where the problem can be reconstructed locally.