How to pass multiple value report parameter in the URL?

Hi All,

I would like to run the report setting a few parameters. I am forming the URL as below.

https://<servername>/CRMReports/viewer/viewer.aspx?action=run&helpID=<reportname>.rdl&id=%7b<Id>%7d&p:StartDate=<StartDate>&p:UserName=<UserId>&p:EndDate=<EndDate>

When the report runs, the Start Date and End Date parameters are passed correctly to the report, but the UserName parameter isn't. It comes as blank when the report runs. UserName parameter is a multiple values parameter.

Is there any specific way to set the multiple value parameter in the URL? How can I set this parameter so that the report runs with it?

Thanks,

Swaroop