Hi I've the same problem! I find in my jrxml this line: <measure name="nr_fattureMisura" class="java.lang.Long" calculation="Sum" percentageOf=""> <measureExpression><![CDATA[$F{nr_fatture}]]></measureExpression> I must remove the property percentageOf="" to solve the problem. I think it's a iReport bug because I use the property tab to set this field but no value is written in the jrxml! Luigi