Unable to add trusted domain user/groups to CIFS share perms

I am having the same issue. I have joined my ReadyNAS 2100 (RAIDiator 4.2.15) to my Active Directory domain "DOMAIN-A". I also have trust relationships with two other domains in my forest, "DOMAIN-B" ,"DOMAIN-C".

When I try to add "Write-enabled groups:" via "frontview" to my share from the other domains it strips off the domain name. For example, if I add "DOMAIN-A\IT" to the share then add "DOMAIN-B\IT" it will show "IT,IT" when it should show "DOMAIN-A\IT,DOMAIN-B\IT", correct? And to confirm my suspicion, I checked the /etc/frontview/samba/Share.conf file, And it shows:

[IT$] path = /c/IT$ comment = "IT Dept Share" oplocks = 1 admin users = "admin","DOMAIN-A\dave" write list = "@DOMAIN-A\IT","@DOMAIN-A\IT","admin" valid users = "@DOMAIN-A\IT","@DOMAIN-A\IT","admin","nobody"

So I trying browsing to the share in DOMAIN-B, it will not allow me to access it. But DOMAIN-A has access to it.
Now if I go in and edit the "Shares.conf" files to reflect this:

[IT$] path = /c/IT$ comment = "IT Dept Share" oplocks = 1 admin users = "admin","DOMAIN-A\dave" write list = "@DOMAIN-A\IT","@DOMAIN-B\IT","admin" valid users = "@DOMAIN-A\IT","@DOMAIN-B\IT","admin","nobody"

Users in "DOMAIN-A\IT" and "DOMAIN-B\IT" are able to access the share just fine.
So there must be some sort of bug in the "frontview" interface when adding users that are from different domain in the same forest.