Bug in report

Hi world !!

I created a grd file and if the field in the database is NULL or zero 
the row in return XML disappear.
In this example the field sub_seller in database is NULL and the report 
tool return nothing in this point (under the seller col)

This my report :

<gnue:report-output xmlns:gnue="GNUe:Reports:Base" 
xmlns="GNUe:Reports:SimpleTabulation">
   <gnue:report-request>
     <gnue:request-parameter name="con_id">11442</gnue:request-parameter>
   </gnue:report-request>

    <report>
     <section break="page">


      <table width="100%">
         <tablehead>
           <colhead>contract_no</colhead>
           <colhead>name</colhead>
           <colhead>address</colhead>
           <colhead>tel</colhead>
           <colhead>car_number</colhead>
           <colhead>factory_model</colhead>
           <colhead>date_start</colhead>
           <colhead>date_end</colhead>
           <colhead>grand_total</colhead>
           <colhead>seller</colhead>
           <colhead>sub_seller</colhead>
           <colhead>invoice_no</colhead>

         </tablehead>


           <row>
             <col>136</col>
             <col>name</col>
             <col>2</col>
             <col>2310,680,477</col>
             <col>2787</col>
             <col>STRA</col>
             <col>11/12/2009</col>
             <col>11/12/2010</col>
             <col>60.00</col>

               <col>seller</col>

------->>>>> return nothing

             <col>1</col>

           </row>

      </table>

     </section>
    </report>