Problem with external account

[Angel]

Hi guys,

First of all I want to apologize to everybody if this is not the correct forum to solve my question.

I Have a problem with the web client.

I have testing the open source edition with Centos 5 and Active Directory. All works fine, but when I try to configure an external account with someone user, make the test correctly, but when I try to save the configuration, show me an error:

"invalid request: create Datasource invalid schema change: [LDAP: error code -65 attribute 'zimbraPrefFromAddress' not allowed]"

And I don´t know where is the problem. Is this configuration supported only with internal authentification?

Thanks to everybody.