Backing up to a vault with deduplication: Authenication failed

Solved here.

Hello,

this is a test environment, I am testing the deduplication functionality on the latest version of Acronis backup 11.5: I configured a managed vault with deduplication on the the AMS local disk, given the Authenticated users Full NTFS rights, added the Acronis domain account to the Vault admins, but still I get the Authentication failed when trying to perform a backup to the vault:

Autenticazione fallita.
Informazioni aggiuntive:
--------------------
Codice errore: 20
Modulo: 4
LineInfo: 4d5187f54acfdb00
Campi: $module : disk_bundle_vs_43916
Messaggio: Autenticazione fallita.
--------------------
Codice errore: 1079
Modulo: 3
LineInfo: a3cdb7a26e18c8b9
Campi: $module : disk_bundle_vs_43916
Messaggio: Autenticazione fallita.
--------------------

Any help please?