Humm strange, are you sure the settings are correct in the manual setup screen ? if the autodiscovery fails(first setup screen) your server address, username and domain probably are not correct in the second screen, please double check that. Another issue can be that your server requires some provisioning settings that the N9 can't satisfy(N900 does not support provisioning so this is ignored), you can try to check the box "Non provisioning device" in the second setup screen. If this doesn't help we'll need to collect the logs.