SID Error in Forest Trust Environment when adding users to RDS 2012 Collection

Hello,

I have a two way forest trust between two domains. DomA and DomB

DomA hosts all the RDS roles, and DomB hosts all the Virtual Machines and Users. I can add Machines from this domain to the collection but when I try and add a user from DomB to the Collection I get this error.

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On the Window where I select the users I can check names and it comes back correctly.

I am try to publish desktops. I tried to added the users to a Domain Local Group in DomA and add that but I am getting an error that Domain Local Groups can not be used in RDS 2012.

Thanks

Nick