Linebreak problem

How do I make a linebreak in xsl-fo ?
This is what I've tried.

<letter>
  <text>I really need a linebreak in this line <br/> because I need to see how it' done</text>
</letter>

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:fo="http://www.w3.org/1999/XSL/Format" version="1.0">
  <xsl:template match="/">
    <fo:root xmlns:fo="http://www.w3.org/1999/XSL/Format">
      <fo:layout-master-set>
	<fo:simple-page-master master-name="frame"
			       page-height="297mm" page-width="209mm"
			       margin-left="0mm" margin-right="0mm">
	  <fo:region-body region-name="frame-body"/>
	</fo:simple-page-master>
      </fo:layout-master-set>
      <fo:page-sequence master-reference="frame">
	<fo:flow flow-name="frame-body" font-family="Times">
	    <fo:block>
              <xsl:value-of select="letter/text"/>
	    </fo:block>
        </fo:flow>

  <xsl:template match="br">
    <fo:block/>
    <xsl:apply-templates/>
  </xsl:template>