Hi everyone : I've experiencing a strange problem with some reports. After finishing the report design with ireport, all runs fine and the report output is ok. This is the report query : SELECT COD_INDICADOR,TO_DATE(FECHA_VALOR, 'DD/MM/YYYY') AS DIA, SUM(VALOR) FROM YELL_BUSSINESS_DATA WHERE FECHA_VALOR >= $P{FechaInicial} AND FECHA_VALOR < TO_DATE($P{FechaFinal})+1 AND COD_INDICADOR IN (SELECT COD_INDICADOR FROM YELL_SRV_IND WHERE COD_SERVICIO='PAOL') GROUP BY COD_INDICADOR, TO_DATE(FECHA_VALOR, 'DD/MM/YYYY') ORDER BY COD_INDICADOR, TO_DATE(FECHA_VALOR, 'DD/MM/YYYY') ASC Simply, groups the data by day between two dates. The report generation and publication are ok. But, if we add a time series graphic, with the time period=day (see the first attach), the report works fine with ireport, but after publishing it with jasperserver, we're getting the error java.lang.IllegalArgumentException: Null 'period' argumentDeleting the graphic, the report can be published and run normally. The two parameters are java.util.date class Any idea to solve this? Thanks in advance