How to do change s in AJAX CalendarExtendar control?

I want to give facility to enter Time (supporting culture format) in AJAX CalendarExtendar control along with the date. So I am trying to change AJAX Cotrol Toolkit source code. I have dynamically added one textbox in caldarExtendar control, but I am not able to read it's value. I have made changes in 'CalendarBehavior.js' file. Can anybody help me pls? // Reding value fron textbox var str = document.getElementById('txtHourTextbox').value; // ans : Undefined I have added texbox using the below code : var timeWrapper = $common.createElementFromTemplate({nodeName:"div"},this._footer); this._timeTextBox = $common.createElementFromTemplate({ nodeName:"div", properties : { mode : "time", innerHTML : "
", id : "txtHourTextbox" }, events : this._cell$delegates, cssClasses : [ "ajax__calendar_footer", "ajax__calendar_Hour" ] },timeWrapper);