Subreport depend on Parameter

Hi All,

I have a report and a sub report.

In my main report, the parameter there is , EventID and Org.

In The sub report, the parameter there is EventID.

This EventID is need if the user want to run the report with EventID if not they have to enter "0" and the sub report will suppress.

How can i do that?

I have link the main report and the sub report with EventID.

Thanks in advance.