I can't create a package for the Assets Store

I'm using MacosX (10.6.8) I have the last Unity version and Assets store tools.

When trying to make a package in the assets store I get this message:

Could not create package: Error receiving response from server (403): The remote server returned an error: (403) Forbidden.

In console: Could not create package: Error receiving response from server (403): The remote server returned an error: (403) Forbidden. UnityEngine.Debug:Log(Object) c_AnonStorey19:<>m1F(String) cAnonStorey6:<>m6(AssetStoreResponse) AssetStoreClient:m_18(Pending) System.Collections.Generic.List`1:RemoveAll(Predicate`1) AssetStoreClient:Update() UnityEditor.EditorApplication:Internal_CallUpdateFunctions()