Problem adding new application to server

I'm trying to create a new server app (inheriting from LiteLobby). It compiles with no problems on my workstation, using the Photon SDK libs as references, and I already have the Lite and LiteLobby app's configured and running smoothly at my server on Amazon's Cloud, but when I add MyApp to the PhotonServer.config and restart it I get the following error:

--> CService::OnException() - Exception: CManagedHost::StartApplication()
- Failed to start application in AppDomain: 6 - Could not load file or
assembly 'Photon.SocketServer, Version=2.4.7.0, Culture=neutral,
PublicKeyToken=48c2fa3b6988090e' or one of its dependencies. The
located assembly's manifest definition does not match the assembly
reference. (Exception from HRESULT: 0x80131040)

I am aware that this is a .NET/C# problem, and not Photon's, but I'm finding this behavior very strange since my app is built with working dll's. Is there any restriction that I may not be aware of? I am using VS2010 and .NET 4.0. I tried downgrading to 3.5, but then I got compilation errors saying that the Lite+LiteLobby references wouldn't work in such version...

Any help is welcome, thanks in advance!