Outlook 2010 - Room List does appear empty in room finder / select an available room from a location / building

Exchange 2010, Outlook 2010

I've created a room list distribution group) with two room mailboxes as members of it.

- Via EMC, create a distribution group (Name : Buiding01, alias : Building01)

- Convert to room list DG : set-distribution group -identity "Building01" -roomlist

- Via EMC, create two conference room mailboxes (Roomconf01, Roomconf01)

- Via EMC add Roomconf01 & roomconf02 as members of Buiding01 distribution group

- In Outlook when I schedule a meeting using the room finder I select Building01 in "Show room list" box but the room list is empty.

Any help ?

Regards.