Watchguard VPN connection on MAC. connects just fine but user won't authenticate

[dalearyous]

a mac user is connecting through the SSL VPN watchguard utility. he connects just fine and then goes to finder and does: smb://ip/share and it pops up with a login window. he selects registered user and then types in his active directory username and password. the window just blinks.

i had him try the following:
domain\username
domain/username
FQDM\username
FQDM/username
username@FQDM

nothing seems to work. and it isn't a password issue. he has it right. i remote controlled and tried my credentials and the administrator credentials. nothing. what am i missing? i can ping to and from his machine while connected to the VPN so the connection is there. it is clearly finding smb://ip/share

what gives?