keyboard launch when clicking on text area.

i am building a unity app with windows standalone build.

this app is build for lenovo horizon windows 8 pc which has touch support. But in my login screen i am not able to type anything as the touch keyboard is not launching. we dont want to use keyboard for typing. we need to use windows native touch keyboard for all typing.

we used following code to launch the keyboard but in vain

 #pragma strict
     var inputURL : String = "http://www.unity3d.com";
     private var keyboard : TouchScreenKeyboard;
     // Opens native keyboard optimized for URL entry
     function OnGUI() {
         if (GUI.Button(Rect(0, 10, 200, 32), inputURL))
             keyboard = TouchScreenKeyboard.Open(inputURL, TouchScreenKeyboardType.URL);
         if (keyboard)
             inputURL = keyboard.text;
         }

Please let us know how solve this issue. its a urgent requirement. thanks in advance.

regards Hims