XSLT - Add image id to image path based on condition

I want to write xslt where I need to append the imagecode to image path based on chartcategory , below is not working for me, I think I am on wrong steps, I am not sure how to append imagecode to image path even

<MonthlyReport>
 <MonthlyImages>
     <ChartCategory>rankingSavingsPotential</ChartCategory>
     <ImageCode>30032327</ImageCode>
   </MonthlyImages>
</MonthlyReport>



   <xsl:choose>
         <xsl:when test="/MonthlyReport/MonthlyImages/ChartCategory= rankingSavingsPotential">
            <img src="{concat('../../assets/common/image.aspx?CbmsImageId=',imageCode)}"/>
         </xsl:when>
     </xsl:choose>