ADFS Cusotm Rule "Issuer" does not change.

Hi All,
In ADFS RPT I’m want to define a custom rule like following:

c:[Type == "http://schemas.microsoft.com/ws/2008/06/identity/claims/windowsaccountname"]
 => issue(Type = "http://schemas.xmlsoap.org/ws/2005/05/identity/claims/name",
Issuer = “https://mycompany/”,
OriginalIssuer = “https://mycompany/”,
Value = c.Value, ValueType = c.ValueType);

The above rule does transform WindowsAccountName to name but the value of “Issuer” which I changed to https://mycompany/ is not changed it retains the old value i.e.https://servername/adfs/services/trust"

Is this a bug in ADFS custom claims rule or is “Issuer” a readonly attribute?

Thank,

Panther.