Add-ADGroupMember : A referral was returned from the server???

I'm sure I'm missing something here...

All I want to do is add a user from a child domain to a universal distribution group in a parent domain.  Sounds simple enough right?  WRONG!

Here is the example that the help gives:

-------------------------- EXAMPLE 4 --------------------------
    C:\PS>$user = Get-ADUser "CN=Glen John,OU=UserAccounts,DC=NORTHAMERICA,DC=FABRIKAM,DC=COM" -Server "northamerica.fabrikam.com";
    $group = Get-ADGroup "CN=AccountLeads,OU=UserAccounts,DC=EUROPE,DC=FABRIKAM,DC=COM -Server "europe.fabrikam.com";
    Add-ADGroupMember $group -Member $user -Server "europe.fabrikam.com"
    Description
    -----------
    Adds the user "CN=Glen John,OU=UserAccounts" from the North America domain to the group "CN=AccountLeads,OU=UserAccounts" in the Europe domain.

What I can gather from this is that what I am trying to accomplish SHOULD be possible however I'm missing something critical.  Here is the command I'm trying to run:

Add-ADGroupMember -Identity "CN=Test-Group,OU=Area 51,DC=rootdomain,DC=int" -Members "CN=Homer Simpson,OU=TEST,DC=childdomain,DC=rootdomain,DC=int"

And here is the Error that I'm getting:

Add-ADGroupMember : A referral was returned from the server
At line:1 char:1+ Add-ADGroupMember -Identity "CN=Test-Group,OU=Area 51,DC=rootdomain,DC=int ...+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~+ CategoryInfo          : ResourceUnavailable: (CN=Test-Grou...DC=rootdomain,DC=int:ADGroup) [Add-ADGroupMember], ADReferralException+ FullyQualifiedErrorId : ActiveDirectoryServer:8235,Microsoft.ActiveDirectory.Management.Commands.AddADGroupMember

I've tried adding the:

• -Server "dc01.rootdomain.int:3268"
• -Server "rootdomain.int:3268"
• -Server "rootdomain.int"
• -Server "dc01.childdomain.rootdomain.int:3268"
• -Server "childdomain.rootdomain.int:3268"
• -Server "childdomain.rootdomain.int"

I am logged in as an Enterprise administrator however one of the next things I'm going to try is to pass my credentials to the command.  Any thoughts as to what might be going on?