Jasper Reports: chart based on two columns - jasper-reports

Question

I am designing a report with a chart based on fields of the data set. This is the content of the dataset:
I want to add a bars chart with one bar for each entry in the dataset, so I added the following chart code:
<groupFooter>
<band height="249">
<bar3DChart>
<chart>
<reportElement x="10" y="20" width="540" height="200" uuid="532522d1-b004-47b7-9e2a-ff12ab88c7ed"/>
<chartTitle/>
<chartSubtitle/>
<chartLegend/>
</chart>
<categoryDataset>
<dataset resetType="Group" resetGroup="indicador"/>
<categorySeries>
<seriesExpression><![CDATA[$F{fecha}]]></seriesExpression>
<categoryExpression><![CDATA[0]]></categoryExpression>
<valueExpression><![CDATA[$F{valor}]]></valueExpression>
</categorySeries>
</categoryDataset>
<bar3DPlot>
<plot/>
<itemLabel/>
<categoryAxisFormat>
<axisFormat labelColor="#000000" tickLabelColor="#000000" axisLineColor="#000000"/>
</categoryAxisFormat>
<valueAxisFormat>
<axisFormat labelColor="#000000" tickLabelColor="#000000" axisLineColor="#000000"/>
</valueAxisFormat>
</bar3DPlot>
</bar3DChart>
</band>
</groupFooter>
The problem is that field date is no unique, so the chart doesn't depict the table. I want to set the tag seriesExpression to the combination of fields date and division, because such combination is unique.
How can I do it? I tried putting both fields in the same seriesExpression, but I got an error.
EDIT
I tried putting together both fields: <seriesExpression><![CDATA[$F{fecha}$F{division}]]></seriesExpression>, but I got this errors:

Answer 1

seriesexpression must be an Expression, so if Fecha is a Date something like
<seriesExpression><![CDATA[new SimpleDateFormat("dd/MM/yyyy").format($F{fecha})+" "+$F{division}]]></seriesExpression>