Communication issue with PowerShell. Backup Exec uses Remote Powershell functionality to query for details of the Exchange Environment
Force Local PowerShell for backups by creating following registry key on Exchange Mailbox Server:
HKLM\Software\Veritas\Backup Exec for Windows\Backup Exec\Engine\Exchange.
DWORD Value name: PowerShellOptions.
DWORD value = 1
HKLM\Software\Veritas\Backup Exec for Windows\Backup Exec\Engine\Exchange
DWORD Value name: PowerShellOptions.
DWORD value = 1
Create the following key on the Exchange Server(s)
1. Go to Start > Run > Regedit
Warning: Incorrect use of the Windows registry editor may prevent the operating system from functioning properly. Great care should be taken when making changes to a Windows registry. Registry modifications should only be carried-out by persons experienced in the use of the registry editor application. It is recommended that a complete backup of the registry and workstation be made prior to making any registry changes.
2. Locate and select the following registry key:
HKEY_LOCAL_MACHINE\SOFTWARE\Software\Veritas\Backup Exec for Windows\Backup Exec\Engine\Exchange.
3. Select Edit | New
4. Select "DWORD (32bit)" as the Data Type, and click OK.
5. Type PowerShellOptions in the Value Name box.
6. Click OK to save changes and then exit Registry.

7. Restart the Backup Exec Remote Agent Service on the Exchange Server(s).