Oracle Message RMAN-06275 - invalid number of days specified for report : string days

ERRORinvalid number of days specified for report : string days
CAUSEThis message is issued in response to the REPORT NEED RECOVERY WINDOW OF n DAYS or REPORT NEED BACKUP DAYS n command when an invalid number of days was specified in input command.
ACTIONThe number of days specified in REPORT command must be greater than zero.