ComboBox with Tree

Hi friends,

I want to create a ComboBox with a Tree structure options.

Here is the code but doesn't work:

//create the Tree control

var oTree = new sap.ui.commons.Tree("tree");

oTree.setTitle("Explorer");

oTree.setWidth("100%");

oTree.setHeight("auto");

oTree.setShowHeaderIcons(true);

oTree.setShowHorizontalScrollbar(false);

//create Tree Nodes

var oNode1 = new sap.ui.commons.TreeNode("node1", {text:"Computer", icon:"images/system.gif", expanded: true});

var oNode2 = new sap.ui.commons.TreeNode("node2", {text:"OSDisk (C:)", icon:"images/disk.gif", expanded: true});

var oNode3 = new sap.ui.commons.TreeNode("node3", {text:"Program Files", icon:"images/folder.gif"});

var oNode4 = new sap.ui.commons.TreeNode("node4", {text:"Windows", icon:"images/folder.gif"});

var oNode5 = new sap.ui.commons.TreeNode("node5", {text:"Mass Storage (USB)", icon:"images/disk.gif"});

var oNode6 = new sap.ui.commons.TreeNode("node6", {text:"Network", icon:"images/network.gif"});

oNode1.addNode(oNode2);

oNode1.addNode(oNode5);

oNode2.addNode(oNode3);

oNode2.addNode(oNode4);

//add Tree Node root to the Tree

oTree.addNode(oNode1);

oTree.addNode(oNode6);

// Create a ComboBox

var oComboBox2 = new sap.ui.commons.ComboBox("ComboBox2", {tooltip:"City", displaySecondaryValues:true, value:"Walldorf", "association:Tree" : oTree});

Could you help me or give me some advice?

Thank you!