problem with require validation control

hi

i use these code to uploading  image

   <asp:UpdatePanel ID="Upbdt1" runat="server">
    
    <ContentTemplate>
    <asp:ModalPopupExtender DropShadow="true" ID="ModalPopupExtender1"  
            PopupControlID="PnPopup1" runat="server" TargetControlID="BtnPopup1" 
             >
    </asp:ModalPopupExtender>
    <asp:Button ID="BtnPopup1" OnClick="BtnPopup_Click" runat="server" Text="select image" CssClass="DPC9_Img1" BorderStyle="Solid" BorderWidth="0px" BorderColor="White" />
    <asp:Panel ID="PnPopup1" runat="server" BackColor="White"  
            CssClass="panel">
        <asp:ImageButton ID="ImageButton3" runat="server" ImageUrl="~/image/close.png" />
   <br />
        <asp:FileUpload ID="fup1" runat="server" 
            ToolTip="click" />
  
     <asp:Button ID="BtnUpload1" OnClick="BtnUpload_Click"  runat="server" Text="load" />
    </asp:Panel>
    </ContentTemplate>   
    <Triggers>
    <asp:PostBackTrigger ControlID="BtnUpload1" />
    
    </Triggers>
    
    </asp:UpdatePanel>

and i use <asp:RequiredFieldValidator> 

my problem is that

1-when i click on BtnPopup1 when popup window Appear  <asp:RequiredFieldValidator>  show error message i want this control show error when i click other button not  BtnPopup1 button

2-when popup window appear i choose file from file up load and when i click on BtnUpload1 button it didn't do any thing it didn't exit from popup window and didn't do codes that i wrote on  BtnUpload1 _click event.

this is BtnUpload1 _click event 

  protected void BtnUpload1_Click(object sender, EventArgs e)
    {

        string path = Server.MapPath(".") + "\\../image/House\\";

        string[] validext = { ".jpg", ".gif", ".png", ".rar" };
        string ext =
            System.IO.Path.GetExtension(AsyncFileUpload1.PostedFile.FileName);
        if (Array.IndexOf(validext, ext.ToLower()) < 0)
        {
            lblMessage.Text = "please enter correct format";
            return;
        }


        string filename = System.IO.Path.GetFileName(fup1.PostedFile.FileName);


        while (System.IO.File.Exists(path + "\\" + filename))
            filename = "1" + filename;

       


        if (fup1.HasFile)
        {
            try
            {
     
                if (fup1.PostedFile.ContentLength < 105000)
                {
                
                    fup1.PostedFile.SaveAs(Server.MapPath("~/Upload") + System.IO.Path.DirectorySeparatorChar + AsyncFileUpload1.PostedFile.FileName);

                    
                    Label20.Text = "File " + fup1.PostedFile.FileName + " uploaded successfully.";
                }
                else
                {
                    
                    Label20.Text = "File size of " + Convert.ToString(fup1.PostedFile.ContentLength / 1024) + " KB is exceeding the uploading limit.";
                }
            }
            catch (Exception ex)
            {
                // error message
                Label20.Text = "Some problem occurred while uploading the file. Please try after some time.";
            }
        }
        else
        {
            // warning message
            Label20.Text = "Please choose a file to upload.";
        }

        AsyncFileUpload1.PostedFile.SaveAs(path + filename);

        SqlCommand _cmd = new SqlCommand("Fileup1", _cn);
        _cmd.CommandType = CommandType.StoredProcedure;
        string data = Server.UrlDecode(Request.QueryString["BehCode3"]);

        _cn.Open();
        _cmd.Parameters.AddWithValue("@image", fup1.FileBytes);
        _cmd.Parameters.AddWithValue("@Behcode", data);

        _cmd.ExecuteNonQuery();
        _cn.Close();








    }

Best Regards