CRM Report URL Parameter

Hello All,

In our fetchxml based SSRS report deployed to CRM, we have a parameter User which is being populated from a dataset. This parameter uses the systemuserid as a Value field and UserName as a Display field.

In order to populate this parameter value dynamically, I am trying to pass a system user GUID value. But when the report render the parameter comes blank as the value is not recognized.

&p:UserName=<GUID>

Am I passing the parameter correctly? The same seems to work for all other parameter for the report (datetime parameter, text parameter). Is there a different way to pass this parameter which is effectively a CRM entity reference?

Thanks,

Swaroop