asp.net javascript message not showing up
<p>I have a button and onclick is set to this method which should display a simple JS alert pop up window:</p>

<pre><code>string message = "File is already open. &lt;br&gt;Please close the file and try again.";
    System.Text.StringBuilder sb = new System.Text.StringBuilder();
    sb.Append("&lt;script type = 'text/javascript'&gt;");
    sb.Append("window.onload=function(){");
    sb.Append("alert('");
    sb.Append(message);
    sb.Append("')};");
    sb.Append("&lt;/script&gt;");
    ClientScript.RegisterClientScriptBlock(this.GetType(), "alert", sb.ToString());
</code></pre>

<p>I have used the code above before and it has worked but not this time.
The only difference is that I was using master pages for the other site and not for this one, and this one also has a timer going.</p>

<p>Is there anything JS related to load in the <code>&lt;head&gt;</code> of the aspx page?</p>

<pre><code>protected void btnToCSV_Click(object sender, EventArgs e)
    {
        try
        {
            StreamWriter writer = new StreamWriter(@"\\server location\test.csv");

            Some writer.write stuff...

            writer.Close();
        }
        catch (Exception ex)
        {
            lblMessage.Visible = true;
            string message = "File is already open. Please close the file and try again.";
            ClientScript.RegisterClientScriptBlock(
               this.GetType(),
              "alert",
              string.Format("alert('{0}');", message),
              true);

        }
}
</code></pre>
