@Override public void validate(final Form< ? > form) { final Date fromDate = fromDatePanel.getConvertedInput(); final Date toDate = toDatePanel.getConvertedInput(); if (toDate != null && fromDate != null && fromDate.after(toDate) == true) { toDatePanel.getDateField().error(getString("fibu.buchungssatz.error.invalidTimeperiod")); } } });