Alert box ( or msgbox ) is not displayed on a page

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C#

ASP.NET

hello friends,
I am new to ASP.net. I have designed a page by using some images for background. Everything was fine. Bt now whien i try to display a message boc or any alert msg after saving the data it is not displayed. Data is saved properly. bt message is not displayed. Is it because of Images? How to display a msg or alert box above those images. Please help me out. my code for alert box is as follows:

void CallToast(String msg, String cls)
    {
       System.Text.StringBuilder sb = new System.Text.StringBuilder();
       sb.Append("<script language='javascript'>");
       sb.Append("toast("+"" + msg + ""+","+"" + cls + ""+");");
       sb.Append("</script>");
     ScriptManager.RegisterStartupScript(this, this.GetType(), "ajax", sb.ToString(), false);

    }

  protected void Button1_Click(object sender, EventArgs e)
   {
       try
       {
           sqlhelper = new SQLHelper();
            query = String.Format("Insert into Issues(IssueId,Name,EmailId,ContactNumber,ModelNo,Issue,ToDo)values('{0}','{1}','{2}','{3}','{4}','{5}','{6}')",generateId(),TextBox1.Text,TextBox2.Text,TextBox3.Text ,TextBox4.Text,TextBox5.Text,TextBox6.Text );
          long r =  sqlhelper.ExecuteNonQuery(query);
          if (r == 0)
          {
              CallToast("Sorry! Please try again", "toast-error");
          }
          else
          {
              CallToast("Saved Successfully", "toast-success");
          }
       }
       catch (Exception ex) { }
   }