Add Send As permissions to a dist group via security group

Could you please assign the permissions via powershell :

Add-ADPermission <distribution group> -ExtendedRights Send-As -User <security group> -AccessRights ExtendedRight | fl

I tried the above command and I get the same results as the MMC.   The security group is added successfully to the Send As proprerty, but the permissions are still not working.

FYI  we have Exchange 2010 SP2 RU4  installed.