Unable to create new user with Domain authentication

hi,
just been trying to add new user with Domain authentication - constantly getting following error.
Using RDM or DPS client i can add user with no isuess

$new_user = New-RDMUser -Login 'username@ourdomain' -AuthentificationType Domain -SetUser

error:

New-RDMUser : Parameter set cannot be resolved using the specified named parameters.
At line:1 char:6
+ $a = New-RDMUser -Login 'username@ourdomain' -Authentificatio ...
+      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidArgument: (:) [New-RDMUser], ParameterBindingException
    + FullyQualifiedErrorId : AmbiguousParameterSet,RemoteDesktopManager.PowerShellModule.NewRDMUserCommand

Any hint how to fix this ?
thx