4.0.5.0 WinPhone8 vs. 4.0.0.4: App doesn't create rooms.

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Hello,

I'm trying to update my 4.0.0.4 based game for using the 4.0.5.0 dlls. Referencing the new dlls and modifiyng the code to create the rooms using TypedLobby.Default, the client connects but is unable to create the room within.
What do I need to change in the code? I'm using a custom game application on the server side, based on LoadBalancing.

Any help?

Flavio