Ireport ajuda

que erro e este?

net.sf.jasperreports.engine.JRException: No report compiler set for language : null
        at net.sf.jasperreports.engine.JasperCompileManager.getCompiler(JasperCompileManager.java:508)
        at net.sf.jasperreports.engine.JasperCompileManager.compileReport(JasperCompileManager.java:219)
        at net.sf.jasperreports.engine.JasperCompileManager.compileReport(JasperCompileManager.java:205)

nao consigo descobrir a causa ja vasculhei a net e nada,alguem pode dar uma luz?
Obrigado.