Formatting a Textbox (date) like masked

<![CDATA[<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="cc1" %>]]>

<asp:scriptmanager id="ScriptManager1" runat="server" xmlns:asp="#unknown">
    </asp:scriptmanager>

<asp:textbox id="txtFrom" runat="server" maxlength="10" onblur="CalculateDays();" width="100" xmlns:asp="#unknown"></asp:textbox> 
 <img id="Img2" src="Images/Calendar.png" runat="server" alt="" />
<cc1:calendarextender id="CalendarExtender2" runat="server" popupbuttonid="Img2" xmlns:cc1="#unknown">
TargetControlID="txtFrom" Format="dd/MM/yyyy">
</cc1:calendarextender>
<cc1:maskededitextender id="MaskedEditExtender1" runat="server" mask="99/99/9999" xmlns:cc1="#unknown">
 MaskType="Date" TargetControlID="txtFrom" PromptCharacter="_">
 </cc1:maskededitextender>