Hi, 'Use null if empty' is advised because if no input parameter is given, Pega will return all results. Sometimes this is desirable, for example when a user has multiple filters to chose from that are dependant on each other. However, if you have a use case where the parameter should always be provided / be required, this checkbox should also be checked to prevent incorrect results.  As an alternative, you can work with default values in the parameter tab to override this behaviour.  Kind regards, Bas