no XML rendered in this example, why not?

I know I'm calling the controller correctly, I get

XML Parsing Error: no element found
<controller>.xml;example
Line Number 1, Column 1:

def example
    xml = Builder::XmlMarkup.new(:indent=>2)
    xml.instruct!
    xml.person
    return xml

    respond_to do |format|
      format.html # index.rhtml
      format.xml { render :xml => xml }
    end
  end