Cannot link mailbox to user in accounts forest

Question

original forest is a single domain configuration named mydomain.com.  A new accounts forest was created named ad.mydomain.com.  This domain is *not* a subdomain of the original domain, but a separate domain in a separate forest.  This forest
also uses a single domain design. (It's a long story) All mailboxes reside in a single mailbox database on an Exchange 2010 server running on Windows Server 2008 R2.  I've used the ADMT to migrate some test accounts to the accounts forest. 
The migration works and the account appears functional, i.e., SID history migrated and the account can still get to shares and files on machines located in the resource forest. 
I then use the disable-mailbox and connect-mailbox commands to setup the linked mailbox.  My test account is user Joe Doakes (as listed in Get-MailboxStatistics), username is jdoakes, mailnickname is jdoakes and SMTP address is [email protected] 
Here is the exact command I am using:
Connect-Mailbox -Identity "Joe Doakes" -Database "Mailbox Database 0448361937" -LinkedDomainController MEDTMPDC01.ad.mydomain.com
-LinkedMasterAccount "CN=Joe Doakes,OU=Testing,OU=Accounts,DC=ad,DC=mydomain,DC=com" -LinkedCredential $cred
to which the command shell replies-
Confirm
Do you want to connect this mailbox to user "mydomain.com/Testing/Joe Doakes" with the alias "JoeDoakes"?
[Y] Yes  [A] Yes to All  [N] No  [L] No to All  [?] Help (default is "Y"):
I've re-entered the credentials for the accounts forest twice.  The canonical name above is the name of the now disabled account in the resource forest.  If I select Y here, it reconnects to the old account and changes the alias from jdoakes
to JoeDoakes.  This behavior is very strange.  I have confirmed the distinguished name used is correct.  Can anyone point out what I am doing wrong?
TIA
Tom

Answer 1

I wanted to update this post in case anyone else runs into this problem.  I wound up opening
a support ticket and spent a day and a half on the phone with Microsoft. 
This issue was the result of several chance problems and my misinterpretation
of the command's results.  To start off, when the command comes back to
say that it wants to connect the mailbox to "mydomain.com/Testing/Joe Doakes", it
really means that it is the disabled account in the Exchange (source) forest to which the
mailbox will be connected.  It will be "linked" to the account in the accounts forest, but the command does not say that.  This behavior is by design.  We also found that I have to specify the alias in the command or a new alias is created that
concatenates the target account's first
and last names.  Last, we found that running a number of
clean-mailboxdatabase commands was the trick that finally made things
work.  To recap, the procedure that worked for me was:
1. Disable-mailbox to disconnect the user in the source forest
2. Verify the mailbox is actually disconnected.  If it does not show up in the
Disconnected Mailbox node in the EMC, run the clean-mailboxdatabase "<database
name>" command
3. Disable the source forest user account.
4. Enter the account forest credential ($cred = get-credential)
5. Connect the mailbox to the linked account.  This is the command that worked for me:
  Connect-Mailbox -Identity "Joe Doakes" -Alias jdoakes
-Database "Mailbox Database 0448361937" -LinkedDomainController MEDTMPDC01.ad.mydomain.com -LinkedMasterAccount "CN=Joe Doakes,OU=Testing,OU=Accounts,DC=ad,DC=mydomain,DC=com" -LinkedCredential
$cred 
6. The new account may not be able to get to the mailbox without running another clean-mailboxdatabase.
I hope this saves someone else a call to Microsoft.