FOP table formatting problem

Does anyone using FOP know what I'm doing wrong  - how I can ensure a
particular column spans 2 rows? Using Fop (0.18.1), I get an error message
saying

" [2WARNING: Number of cell columns under table-row not equal to number of
table-
columns]"

and the entire row is eliminated in the PDF output. Tried using the Table
test cases on Renderx and the w3c FOP site (table_spans.fo) but still get
the same problem.

Would really appreciate any ideas on how to get around this?
Thanks
amit



<fo:table>
     <fo:table-column column-width="5cm"/>
          <fo:table-column column-width="5cm"/>

     <fo:table-row >
               <fo:table-cell number-rows-spanned="2">
                    <fo:block>Column 1</fo:block>
               </fo:table-cell>
               <fo:table-cell number-rows-spanned="1">
                    <fo:block>Column 2</fo:block>
               </fo:table-cell>
     </fo:table-row >

     <fo:table-row >
               <fo:table-cell number-rows-spanned="1">
                    <fo:block>Row Data</fo:block>
               </fo:table-cell>
     </fo:table-row >

</fo:table>


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