Just one pie in report chart if parameter values are equal - charts

Question

Was created pie 3d chart. It has several params. For example, one of them call "errors" and another - "success". Both is Integer. If values are different, for example 10 and 9, all work fine, but if values are equal, it draw like one pie, and in label expression writed only one value.
In this image I set 10 errors and 10 success, but as can be seen, JasperReports draw just 10 success.
I check it in iReport and by generation report in Java, but results was same.
One more example.
<parameter name="access" class="java.lang.Number"/> set 10
<parameter name="configChange" class="java.lang.Number"/> set 10
<parameter name="creating" class="java.lang.Number"/> set 5
<parameter name="deleting" class="java.lang.Number"/> set 10
<parameter name="updating" class="java.lang.Number"/> set 5
<parameter name="objRequest" class="java.lang.Number"/> set 7
<parameter name="unknown" class="java.lang.Number"/> set 8
Result:
jrxml-file:
<pie3DChart>
<chart isShowLegend="true" renderType="draw" theme="default">
<reportElement uuid="1ea2fe12-8478-48a3-8a16-828cb17bc242" positionType="FixRelativeToBottom" mode="Opaque" x="0" y="50" width="430" height="280" backcolor="#CCFFFF"/>
<chartTitle/>
<chartSubtitle/>
<chartLegend/>
</chart>
<pieDataset>
<pieSeries>
<keyExpression><![CDATA[$P{errors}]]></keyExpression>
<valueExpression><![CDATA[$P{errors}]]></valueExpression>
<labelExpression><![CDATA["Error"]]></labelExpression>
</pieSeries>
<pieSeries>
<keyExpression><![CDATA[$P{success}]]></keyExpression>
<valueExpression><![CDATA[$P{success}]]></valueExpression>
<labelExpression><![CDATA["Success"]]></labelExpression>
</pieSeries>
</pieDataset>
<pie3DPlot depthFactor="0.2">
<plot backgroundAlpha="0.1" foregroundAlpha="0.6">
<seriesColor seriesOrder="0" color="#FF0000"/>
<seriesColor seriesOrder="1" color="#0066FF"/>
</plot>
<itemLabel/>
</pie3DPlot>
</pie3DChart>