Currency code Problem

hi Gurus,

Currently we are using 4.6 version.I have created a new currency code RSD (Serbischer Dinar). I have maintained the translation ratio between RSD and USD as 1:1 . I have maintained exchange rate also. But when I try posting a document I am getting an error message :

For the currency code ALE communication is not allowed

Message no. B1 889

Diagnosis

The ISO code assigned to the current currency code is not unique and the primary flag is NOT set. This currency code can therefore not be used for external communication.

Please tell me how to solve this