C# - Get Role Of User In A String Variable?

is there a way i can get the role in a string variable using the below commands....

System.Security.Principal.WindowsIdentity wi = System.Security.Principal.WindowsIdentity.GetCurrent();
System.Security.Principal.WindowsPrincipal wp = new System.Security.Principal.WindowsPrincipal(wi);


i need this for

FormsAuthenticationTicket authTicket = new FormsAuthenticationTicket(1, // version
UserName.Text, // user name
DateTime.Now, // creation
DateTime.Now.AddMinutes(60),// Expiration
false, // Persistent
role); // User data

as string role= wp.IsInRole();
but this is not right