SharePoint:DateTimeControl readonly textbox + SharePoint 2010

my date control id is "dtSummaryDate" Please change the name with your date control id.

<SharePoint:DateTimeControl Enabled="false" runat="server" ID="dtSummaryDate

" DateOnly="true" />

<asp:Content ID="Main" ContentPlaceHolderID="PlaceHolderMain" runat="server">

<script language="javascript" type="text/javascript">

        _spBodyOnLoadFunctionNames.push("ReadOnlyTexbox");

        function ReadOnlyTexbox()

        {

            var x = document.getElementsByTagName("INPUT");

            alert(x.length);

            for (var i = 0; i < x.length; i++) {

                if (x(i).id.indexOf("dtSummaryDate") > 0) {

                   // alert(x(i));

                    //x(i).disabled = 'disabled';

                    x(i).setAttribute('readonly', 'readonly');

                }

            }

         }      

       

    </script>

 </asp:Content>