Exchange DAG Backup failing

Hi,
we have a big problem in backing up an exchange server 2010 DAG with 2 nodes installed on windows 2008 R2 servers.
The backup failed periodically with the error pasted below but now despite all our tests it does not work anymore, each time we launch the job it fails almost immediatly. We double checked the credentials used for the job (it is correctly listed in adjust memory, moidify firmware and replace process level token) on exchange servers. We restarted both exchange servers and backup server and we restarted serveral times acronis servers..
We have tons of logs not getting truncated..
We need some advice.
I attach the export of logs of exchange server failing and the export of the job definition (i deleted the encriptyed passwords from it).
If you give me an email i will private message the Acronis Info output.
Thank you

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Informazioni dettagliate sulla voce del registro
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Tipo: Errore
Data e ora: 5/26/2015 9:41:21 PM
Piano di backup: DAG backup
Attività: Transaction log backup
Codice: 20,250,685(0x135003D)
Modulo: 309
Proprietario:
Messaggio:
Command 'Running backup plan 'DAG backup'' has failed.
Additional info:
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Error code: 61
Module: 309
LineInfo: 4a8728dc8a1c950f
Fields: $module : mms_vs_38573
Message: Command 'Running backup plan 'DAG backup'' has failed.
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Error code: 41
Module: 307
LineInfo: e6792a5ee190dda6
Fields: $module : agent_protection_addon_vs_38573
Message: Failed to execute the command.
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Error code: 29
Module: 307
LineInfo: d63b333701123475
Fields: $module : agent_protection_addon_vs_38573
Message: LaunchBackupCommand: Failed to execute the command.
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Error code: 58
Module: 307
LineInfo: c37471ceffa18278
Fields: $module : agent_protection_addon_vs_38573
Message: No backup items were resolved:
('ArxUri=arx%3a%2f%2fis%2fMDB01','arx::gct::database_2010',{'4B2A7A93-A44F-4155-BDE3-A023C57C9431':'arx::db::infostore_items'})
A generic error of Microsoft Exchange Item Provider.
Failed to browse Microsoft Exchange Server.
Cannot connect to Microsoft Exchange Server.
The Exchange management operation has failed.
An error has occurred while getting the configuration of the Exchange organization.
A generic COM error of the PowerShell adapter.
PowerShell error details: Value cannot be null.
Parameter name: serverSettings
at System.Management.Automation.Internal.PipelineProcessor.SynchronousExecuteEnumerate(Object input, Hashtable errorResults, Boolean enumerate)
at System.Management.Automation.Runspaces.LocalPipeline.InvokeHelper()
at System.Management.Automation.Runspaces.LocalPipeline.InvokeThreadProc()

('ArxUri=arx%3a%2f%2fis%2fMDB02','arx::gct::database_2010',{'4B2A7A93-A44F-4155-BDE3-A023C57C9431':'arx::db::infostore_items'})
A generic error of Microsoft Exchange Item Provider.
Failed to browse Microsoft Exchange Server.
Cannot connect to Microsoft Exchange Server.
The Exchange management operation has failed.
An error has occurred while getting the configuration of the Exchange organization.
A generic COM error of the PowerShell adapter.
PowerShell error details: Value cannot be null.
Parameter name: serverSettings
at System.Management.Automation.Internal.PipelineProcessor.SynchronousExecuteEnumerate(Object input, Hashtable errorResults, Boolean enumerate)
at System.Management.Automation.Runspaces.LocalPipeline.InvokeHelper()
at System.Management.Automation.Runspaces.LocalPipeline.InvokeThreadProc()

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Acronis Knowledge Base: http://kb.acronis.com/errorcode/

Codice evento:

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