Set scroll position in bootstrap modal popup on postback in ASP.Net

hi

How to put ScrollPositionOnPostback for bootstrap modal popup

I use modal on page below are codes:

<script type="text/javascript">
    $(function () {
        $("#Contact").click(function () {
            $('#myModal1').modal('show');
        });
    });
</script>
<div class="modal fade" id="myModal1">
    <div class="modal-dialog">
        <div class="modal-content">
            <div class="modal-header">
                <div id="btnclose">
                    <button type="button" class="close" data-dismiss="modal">&times;</button>
                </div>
                <div class="modal-body">
                    <div id="topadd2M">
                        <div id="DNCRM1">
                            <asp:textbox id="Txtname" runat="server" cssclass="txtnameCM" tabindex="1"></asp:textbox>
                        </div>
                        <div id="DNCRM1">
                            <asp:textbox id="Txtmobile" runat="server" cssclass="txtmobCM" tabindex="2"></asp:textbox>
                        </div>
                        <div id="DnameC7M">
                            <div id="message" class="attenCCM">
                                <asp:label id="Label53" runat="server" cssclass="lblattenC1M">Please insert data correctly </asp:label>
                            </div>
                            <asp:requiredfieldvalidator display="Dynamic" id="RequiredFieldValidator1" runat="server" controltovalidate="Txtname"></asp:requiredfieldvalidator>
                            <asp:requiredfieldvalidator display="Dynamic" id="RequiredFieldValidator2" runat="server" controltovalidate="Txtmobile"></asp:requiredfieldvalidator>
                            <script type="text/javascript">
                                function WebForm_OnSubmit() {
                                    var message = document.getElementById("message");
                                    message.style.display = "none";

                                    if (typeof (ValidatorOnSubmit) == "function" && ValidatorOnSubmit() == false) {
                                        for (var i in Page_Validators) {
                                            try {
                                                if (!Page_Validators[i].isvalid) {
                                                    message.style.display = "block";
                                                    // Reopen modal.
                                                    $('#myModal1').modal('show');

                                                }
                                            } catch (e) {
                                            }
                                        } return false;
                                    } return true;
                                }
                            </script>

here I use validation for textboxes and I use this code for the page:

 MaintainScrollPositionOnPostback="true"

Now here in Modal when I don't insert data and click on the button it will show a message that I should insert data problem is that when I click a button it refreshes the page and goes to the top of Modal I should scroll down until I can see the message

What should I do?

Best regards

Neda