MaskedEditExtender1it's not firing

I dont know why is my MaskedEditExtender1 is not firi开发者_如何转开发ng.. is there any problem in codes?

</asp:ScriptManager>

<div>Enter a New Insurance Carrier Code<asp:Panel ID="Panel1" runat="server" 
        Height="105px" Width="141px">

      <asp:radiobuttonlist id="Radiobuttonlist1" runat="server" Height="83px" 
        onselectedindexchanged="Radiobuttonlist1_SelectedIndexChanged" Width="139px">
      <asp:listitem id="optAutoAssign" runat="server" Selected = "true" value="Auto Assign" />
      <asp:listitem id="optManual" runat="server" value="Manual" />
      </asp:radiobuttonlist>


    &nbsp;<asp:TextBox ID="txtManual" runat="server"></asp:TextBox>
    <ajaxToolkit:MaskedEditExtender
         ID="MaskedEditExtender1" runat="server" 
         TargetControlID="txtManual"   
         Mask="99:99:99"  
         MessageValidatorTip="true"  
         OnFocusCssClass="MaskedEditFocus"  
         OnInvalidCssClass="MaskedEditError"  
         MaskType="Time"  
         AcceptAMPM="True"  
         ErrorTooltipEnabled="True">
    </ajaxToolkit:MaskedEditExtender>

Here is the script I am using and it is working perfectly:

<asp:TextBox ID="fromTimeTextBox" runat="server"></asp:TextBox>

<asp:MaskedEditExtender ID="timeMaskedEditExtender" runat="server" 
    AcceptAMPM="true" Mask="99:99" MaskType="Time" 
    TargetControlID="timeTextBox"/>

Make sure you have registered the AJAXToolKit assembly:

<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit"
    TagPrefix="asp" %>

And using the ToolkitScriptManager:

<asp:ToolkitScriptManager ID="toolkitScriptManager" runat="server">
</asp:ToolkitScriptManager>