You set a date type parameter as a String in a format that BIRT doesn't recognize.
Try the following:
- define the FechaInicio date parameter in some format in the reporteSinDetalle.rptdesign report (yyyy-MM-dd, for instance)
- add the getFechaInicioAsString method to Report.java that will return the date as a String in the yyyy-MM-dd format(or whatever format you defined in the report).