[netcdf-java] Variable rename and joinExisting aggregation error

Hi,
I getting errors when variables are renamed on aggregations. This the smallest examplewhich is reproducing the error: 
<netcdf xmlns="http://www.unidata.ucar.edu/namespaces/netcdf/ncml-2.2";>
    <dimension name="isobaric1" length="1"/>
    <variable name="z700" shape="time isobaric1 lat lon"/>
    <aggregation type="union">
        <netcdf>
            <variable  name="z700" orgName="Geopotential_isobaric"/>
            <aggregation dimName="run" type="joinNew">
                <variableAgg name="Geopotential_isobaric"/>
<netcdf location="system4/19810101/SYSTEM4_ecmf_19810101_129.128_PL_700_0.grb"/> 
            </aggregation>
        </netcdf>
    </aggregation>
</netcdf>

and I getting this error:
SEVERE: AggOuterDimension cant find z700 in file:/home/cofinoa/Desktop/EUPORIAS/apache-tomcat-7.0.34/content/thredds/public/system4/temp/pruebas3.ncml#system4/19810101/SYSTEM4_ecmf_19810101_129.128_PL_700_0.grb; return all zeroes!!!
It appears that the variable name="z700" shape="time isobaric1 lat lon"/> element is producing the error. 

This error is no been generated if I remove the JoinExisting aggregation:
<netcdf xmlns="http://www.unidata.ucar.edu/namespaces/netcdf/ncml-2.2";>
    <dimension name="isobaric1" length="1"/>
    <variable name="z700" shape="time isobaric1 lat lon"/>
    <aggregation type="union">
<netcdf location="system4/19810101/SYSTEM4_ecmf_19810101_129.128_PL_700_0.grb"> 
            <variable  name="z700" orgName="Geopotential_isobaric"/>
        </netcdf>
    </aggregation>
</netcdf>
I t hink it's an error been produced by the joinExisting aggregation combined with the <variable name="z700" orgName="Geopotential_isobaric"/> entry. 

In principle the ncml appears to be correct any ideas?

Regards

Antonio

--
Antonio S. Cofiño
Grupo de Meteorología de Santander
Dep. de Matemática Aplicada y
       Ciencias de la Computación
Universidad de Cantabria
http://www.meteo.unican.es