Unable to retrieve aggregationValue from below mentioned xml

<ContentItem xmlns="http://ift.tt/1LDy0Hm" type="GenericMarketingContent">
      <TemplateId>OneRecordBanner</TemplateId>
      <Name>One Record Banner</Name>
      <Property name="title">
        <String>Recommended</String>
      </Property>
      <Property name="image">
        <String>green.gif</String>
      </Property>
      <Property name="alt_text">
        <String>Image Alt text</String>
      </Property>
      <Property name="record_list">
        <RecordSelection xmlns="http://ift.tt/1Bcusux">
          <RecordList>
            <Record key="pp500231036301401000091" aggregationKey="grp_id">
              <aggregationValue>pp5002310363</aggregationValue>
              <label>Deer Stags Manager Mens Slip On Shoes</label>
            </Record>
          </RecordList>
          <recordLimit>1</recordLimit>
        </RecordSelection>
      </Property>
</ContentItem>

/ContentItem/Property[@name='record_list']/RecordSelection/RecordList/Record/aggregationValue/text()` is not fetching value. I am able to get all other values for other property tags but not this one.Can someone tell me where I am going wrong?