Property UserName was not found in asp.net membership GetUsersInRole

 Hi, I have used the method Membership.GetAllUsers..and worked fine out the box...now I want to get only users with a specifi role so i used Roles.GetUsersInRole("Admin")
but i am getting an error that the Property UserName Was not found...which means it's not included, but i want to be able to edit a user based on username...how can this be achieved? Thanks
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