How to transform then filter a SourceCache?

[LJN-hzleaper]

RepoConnections.Connections // RepoConnections.Connections is a SourceCache<Connection, string>
                .Connect()
                .Transform(connection => new ClientProxy(connection))
                .ObserveOn(RxApp.MainThreadScheduler)
                .Bind(out _clients) //_clients is a ReadOnlyObservableCollection<ClientProxy>
                .Filter(proxy => proxy.Selected) 
                .Bind(out _checkedClients) // _checkedClients is a ReadOnlyObservableCollection<ClientProxy>
                .Count()
                .BindTo(this, x => x.CheckedClientCount);

Above is my code. _clients is bound to a view to allow user to change the Selected property of each item. What I want is when the Selected property of a ClientProxy in _clients changes, filter _clients and update _checkedClients and CheckedClientCount. But the code above doesn't work, it only update _checkedClients and CheckedClientCount at the binding time.

[LJN-hzleaper]

After add a call .AutoRefresh(proxy => proxy.Selected), my code works as expected.