Requirement and tasks relationship

I tried to create a standard report which filter out the requirement and tasks. The template is as below.

    <xsl:for-each select="Requirement">
       <tr>
          <td>
            <xsl:value-of select="RequirementId"/>
          </td>
          <td>
            <xsl:attribute name="style">
              padding-left: <xsl:value-of select="string-length(IndentLevel)*2"/>px;
            </xsl:attribute>
            <xsl:if test="IsSummary='True'">
              <b>
                <xsl:value-of select="Name"/>
              </b>
            </xsl:if>
            <xsl:if test="IsSummary='False'">
              <xsl:value-of select="Name"/>
            </xsl:if>
          </td>
          <xsl:for-each select='Tasks/Task'>
			<tr>
			  <td>
				<b>
				  <xsl:value-of select="TaskId"/>
				</b>
			  </td>
			  <td>
				<xsl:value-of select="Name"/>
			  </td>
			</tr>
		  </xsl:for-each>
		</tr>
      </xsl:for-each>

I find that the second for-each is not working to retrieve the Task information.

May I know if it is possible to do so?

And if there is any document with corresponding information on the artifects relationship?