XML : Xslt 1.0 - getting tag values after xsl:for-each

I have the following XML:

  <jobDetails>    <Question>      <QuestionNumber>1</QuestionNumber>      <QuestionResponse>        <Response>ResponseOne</Response>      </QuestionResponse>    </Question>    <Question>      <QuestionNumber>2</QuestionNumber>      <QuestionResponse>        <Response>ResponseTwo</Response>      </QuestionResponse>    </Question>  </jobDetails>    

I am using XSLT 1.0 to get the value of the Response if the question number is 2.

I can output the value of the response by doing this:

  <xsl:for-each select="jobDetails/Question">      <xsl:variable name="theSet" select="QuestionNumber[string(.)='2']" />        <xsl:if test="$theSet">          <response>              <xsl:value-of select="QuestionResponse/Response" />          </response>      </xsl:if>  </xsl:for-each>    

... but I need to further query the response and output a value depending upon what the response is.

I have tried this:

  <xsl:for-each select="jobDetails/Question">      <xsl:variable name="theSet" select="QuestionNumber[string(.)='2']" />        <xsl:if test="$theSet">          <xsl:when test="QuestionResponse/Response = 'ResponseOne'"><Response>SomeValue</Response></xsl:when>           <xsl:when test="QuestionResponse/Response = 'ResponseTwo'"><Response>SomeOtherValue</Response></xsl:when>      </xsl:if>  </xsl:for-each>    

... but the XSLT does not validate.

Thanks in advance for any assistance.