Exchange Migration 2010 to 2013 prepare mailbox

Hello everyone.
we are migrating users a (cross-forest) scenario using FIM and ADMT.
moving the users and computers is working fine. synchronization between forests is working fine also as I can see 2010 mailboxes in exchange 2013 GAL as contacts. the issue appeared when I Ran the preparation command :
.\Prepare-MoveRequest.ps1 -Identity migtest@domain1.loc -Remote ForestDomainController DC.domain1.loc -RemoteForestCredential $Remote -LocalForestCredential $Local -LocalForestDomainController dc.domain2.local -UseLocalObject

and the error looks like this :
C:\Program Files\Microsoft\Exchange Server\V15\Scripts\Prepare-MoveRequest.ps1 : Error looking up source MBX
migtest@domain1.loc in source forest.
At line:1 char:1
+ .\Prepare-MoveRequest.ps1 -Identity migtest@domain1.loc -RemoteForestDomainControll ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [Write-Error], WriteErrorException
    + FullyQualifiedErrorId : Microsoft.PowerShell.Commands.WriteErrorException,Prepare-MoveRequest.ps1

0 mailbox(s) ready to move.

your help is highly appreciated..
thanks in advance.
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Check if  msExchMailboxGUID and PrimarySMTPAddress at the target is same and go through the articles below:

I would also try with mail enabled user. Let me know how you get on with it.

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csh2010Author Commented:
Dear Amit
I'm already aware of the links you provided me.
the issue is related to the source MBX thank you for your help.

Have you checked with integrity check on source MBX for any error??

I am sure about to follow road-map for Cross forest migration provided by Microsoft please check carefully if in between you are missing something.

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