welcome.ascx not rendered by render method on Sharepoint masterpage

Question

Hi all, I have the following problem:
writing this method on a sharepoint default masterpage (blueband.master)

protected override void Render(HtmlTextWriter output) 
{
    StringWriter w;
    w = new StringWriter();

    HtmlTextWriter myoutput = new HtmlTextWriter(w);
    base.Render(myoutput);

    myoutput.Close();

    m_sXHTML = w.GetStringBuilder().ToString();
    output.Write(m_sXHTML);
}

everything works fine but the usercontrol welcome.ascx is not rendered except the content ("welcome system account" without any tag) and it is the first thing to be rendered at the beginning of the page and before <!CDOCTYPE tag.

Any ideas on how to solve it and why it happens?