RequiredFieldValidator not correct working when i use ScriptManager.RegisterStartupScript

Question

When I fired btn event. after refresh page and RegisterStartupScript my asp.net validators not working corectly

protected void btnSumbit_Click(object sender, EventArgs e)
{
    NotifyShow("example");
}
public void NotifyShow(string msg)
{
    string myScript = string.Format("ShowMessages('{0}','{1}');", msg, "type");
    StringBuilder str = new StringBuilder();

    str.Append(myScript);

    ScriptManager.RegisterStartupScript(this.Page, this.Page.GetType(),
        "AlertJS", str.ToString(), true);
}

this HTML

<form id="form1" runat="server">
<div id="main">
    <asp:TextBox runat="server" ID="txtb1" ValidationGroup="g1" ></asp:TextBox>
    <asp:RequiredFieldValidator ID="rfv" runat="server" ControlToValidate="txtb1" Text="not  valid" ValidationGroup="g1"></asp:RequiredFieldValidator>
    <asp:Button runat="server" ID="btnSumbit" ValidationGroup="g1" OnClick="btnSumbit_Click"/>
</div>
</form>

this javascript

function ShowMessages(messageText, type) {
var images = "";

document.getElementById("main").innerHTML = document.getElementById("main").innerHTML + "<div id='MessagePopUp' class='" + type + "' title='Error message'>" +"" +"<p id='MessageText' style='direction: rtl; margin: 0px auto; padding: 5px;'>" + messageText + "</p>" +"</div>";

var popUp = document.getElementById("MessagePopUp");

$("#MessagePopUp").show("slide", 1000, function () {
    $("#MessagePopUp").hide("slide", 2000, function () {

        document.getElementById("main").removeChild(popUp);
    });
}).delay(4000);}

Answer 1

i resolve that when changing my js code to :

function ShowMessages(messageText, type) {
    var html='<div id="MessagePopUp" class="' + type + '" title="Error message"><p id="MessageText" style="direction: rtl; margin: 0px auto; padding: 5px;">' + messageText + '</p></div>';
    addElement('main', 'div', 'tempElement', html);
   var popUp = $("#MessagePopUp");

    $("#MessagePopUp").show("slide", 1000, function () {
        $("#MessagePopUp").hide("slide", 2000, function () {
            removeElement('tempElement');
        });
    }).delay(4000);
}
function addElement(parentId, elementTag, elementId, html) {
    // Adds an element to the document
    var p = document.getElementById(parentId);
    var newElement = document.createElement(elementTag);
    newElement.setAttribute('id', elementId);
    newElement.innerHTML = html;
    p.appendChild(newElement);
}
function removeElement(elementId) {
    // Removes an element from the document
    var element = document.getElementById(elementId);
    element.parentNode.removeChild(element);
}