Validation rule is not working properly. It doesn't let me to save the record with status completed, if I didn't select the two fields. When I select one, it should show the error, that I need to select another one, but in practice, it doesn't show the error and lets me to save the record. OutsideTap__c is picklist, PRVFitted is using the global picklist values.
AND( ISPICKVAL(Status, "Completed"), ISBLANK(TEXT(OutsideTap__c)), ISBLANK(TEXT(PRVFitted__c)) )