Q:

ReactiveUI ObservableAsPropertyHelper throws Cannot be converted to type exception

I'm trying to use ObservableAsPropertyHelper in order to set a readonly Property, but no matter what I try I can't seem to get it working as I expect. 
I can distill it into a single test (using ReactiveUI 4.3.2.0, Nunit. Framework and Should, all from NuGet)
[TestFixture]
public class ObservableAsPropertyHelperTests : ReactiveObject 
{
    private bool _Updated;

    public bool Updated
    {
        get { return _Updated; }
        set { this. RaiseAndSetIfChanged(x => x.Updated, value); }
    }

    [Test]
    public void ShouldSetProperty()
    {
        var input = new Subject<bool>();
        var propertyHelper = input. ToProperty(
                source: this, 
                property: x => x.Updated);//Exception here 

        input. OnNext(true);

        this. Updated. ShouldBeTrue();
    }

but this results in 
System. ArgumentException : Object of type 'ReactiveUI.ObservableAsPropertyHelper`1[System. Boolean]' cannot be converted to type 'System. Boolean'. 
   at System. RuntimeType. TryChangeType(Object value, Binder binder, CultureInfo culture, Boolean needsSpecialCast)
   at System. RuntimeType. CheckValue(Object value, Binder binder, CultureInfo culture, BindingFlags invokeAttr)
   at System. Reflection. RtFieldInfo. InternalSetValue(Object obj, Object value, BindingFlags invokeAttr, Binder binder, CultureInfo culture, Boolean doVisibilityCheck, Boolean doCheckConsistency)
   at System. Reflection. RtFieldInfo. SetValue(Object obj, Object value, BindingFlags invokeAttr, Binder binder, CultureInfo culture)
   at ReactiveUI.OAPHCreationHelperMixin. ToProperty[TObj,TRet](IObservable`1 This, TObj source, Expression`1 property, TRet initialValue, IScheduler scheduler, Boolean setViaReflection) in y:\Dropbox\ReactiveUI_External\ReactiveUI\ObservableAsPropertyHelper.cs:line 184#0
   at RxUILearning. ObservableAsPropertyHelperTests. ShouldSetProperty() in C:\Dev\RxUILearning\ObservableAsPropertyHelperTests.cs:line 45#1

I can verify the paramaters being passed in to
    //   source:
    //     The ReactiveObject that has the property
    //
    //   property:
    //     An Expression representing the property (i.e.  'x => x.SomeProperty'

And after looking through the source on GitHub I can see that by calling 
var propertyHelper = input. ToProperty(source: this, property: x => x.Updated, setViaReflection:false);

my code avoids the Exception, but also fails the test. 
How can I avoid Doing It WrongTM? 

A:

_Updated should actually be an ObservableAspropertyHelper
[TestFixture]
public class ObservableAsPropertyHelperTests : ReactiveObject 
{
    private ObservableAsPropertyHelper<bool> _Updated;

    public bool Updated
    {
        get { return _Updated. Value; }
    }

    [Test]
    public void ShouldSetProperty()
    {
        var input = new Subject<bool>();
        input. ToProperty(
                source: this, 
                property: x => x.Updated);//Now should work

        input. OnNext(true);

        this. Updated. ShouldBeTrue();
    }

