Hi,
I tried several times on setup a SERVERNAME\USERA from the "Home-Report Manager --> Site Settings --> Security --> New Role Assignment..
I also checked it already have the roles (System Administrator, System User) being assigned
When I try to run the report remotely via http://ThisISdomainNameURL/Reports_SQLEXPRESS/Pages/Report.aspx?ItemPath=
User 'SERVERNAME\USERA' does not have required permissions. Verify that sufficient permissions have been granted and Windows User Account Control (UAC) restrictions have been addressed
The permissions granted to user 'SERVERNAME\USERA' are insufficient for performing this operation (rsAccessDenied)