report by multiple parameter with OR rela

[heliang(Legacy Member)]

I am trying to create a report with three parameters (date, license number and application number). I want report by License Number or Application number in the date that I put in. I trying following in Record Selection:
1.
{Command.LICENSE_NO} = {?License Number} or
{Command.LICENSE_ID} = {?Application Number}

2.
if isnull({?License Number}) = false then
{Command.LICENSE_NO} = {?License Number};
if isnull({?Application Number})=false then
{Command.LICENSE_ID}={?Application Number};

** license_id is the application number(number). license number(string)

but both of them do not work. somehow I can not leave Application number empty.

Please Help!!!