When I use Powershell to add -GrantSendOnBehalfTo permissions, command runs, but no settings are modified.

I'm trying to enable one user (BBBB) to be able to send emails from another users account (CCCC). In the past, I've given other users (4 of them) the same ability using Powershell with Office 365. But now, while the command runs successfully, the change is not made.

I run the command: Set-Mailbox CCCC -GrantSendOnBehalfTo @{add="BBBB"}

and I get this message: WARNING: "The command completed successfully but no settings of 'CCCC' have been modified."

I've tested it with other user combinations and the same thing happens. I've also checked that I can make other changes like adding or removing FullAccess permissions to mailboxes and adding and removing access to individual calendars and those work fine.

I'm stumped as to why the command seems to run, but won't effect the change.
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K BCommented:
Thomas WheelerCommented:
That would say it has already been set. Did you run get-mailbox bbbb and check the value?

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mhoughtelingAuthor Commented:
KB - I've played with the syntax by including -identity and using the email address vs. the username. Same thing.
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mhoughtelingAuthor Commented:
Thomas - I have confirmed that the user already did not have permissions nor does he have permissions after I run the command using this lovely query that I've found.

Get-RecipientPermission  CCCC | Where { ($_.IsInherited -eq $False) -and -not ($_.Trustee -like “NT AUTHORITY\SELF”) } | Select Trustee, AccessControlType, AccessRights

as it shows the 4 other users I've given access to.

get-mailbox bbbb just gives the Name, Alias, ServerName, and ProhibitSendQuota.
K BCommented:
why the extra characters... just use upn

Set-Mailbox -Identity John -GrantSendOnBehalfTo Suzan
K BCommented:
Set-Mailbox -Identity John@contoso.com -GrantSendOnBehalfTo Suzan@contoso.com

just like that.
what are your results
K BCommented:
Add-RecipientPermission (send-as)
Add-MailboxPermission (full access)
Set-Mailbox (send on behalf as)
mhoughtelingAuthor Commented:
It's been a long day. I wanted to add SendAs permission so yes, GrantSendonbehalfTo was already set; I wanted to see it as SendAs.

Thanks guy.
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