Undefined Exception with WF4 RC

When calling my workflow (dynamically) I get the following exception:

The following errors were encountered while processing the workflow tree: "DynamicActivity": private activity implementation "1: DynamicActivity" has the following validation error: compiler error encounters processing expression "TryCast (simplerule_out, OutputBase2)". The type 'OutputBase2' is undefined.

"DynamicActivity": Private implementation of activity "1: DynamicActivity" has the following validation error: Compiler error encounters "Res" processing expression. The type 'OutputBase2' is undefined.

"DynamicActivity": Private implementation of activity "1: DynamicActivity" has the following validation error: Compiler error encounters "Res" processing expression. The type 'OutputBase2' is undefined.

"DynamicActivity": Private implementation of activity "1: DynamicActivity" has the following validation error: compiler error (s) encountered a processing expression "New list (OutputBase2)". The type 'OutputBase2' is undefined.

The workflow is very simple and works great on VS 2010 beta 2!

All I'm trying to do is create a new list of my abstract custom type "OutputBase2".

public class OutputBase2
{
    public OutputBase2() { }

    public bool Succeeded { get; set; }
}

class Example
{
    public void Exec()
    {
        ActivityBuilder builder = new ActivityBuilder();
        builder.Name = "act1";
        var res = new DynamicActivityProperty { Name = "Res", Type = typeof(OutArgument<List<OutputBase2>>), Value = new OutArgument<List<OutputBase2>>() };
        builder.Properties.Add(res);
        builder.Implementation = new Sequence();
        ((Sequence)builder.Implementation).Activities.Add(new Assign<List<OutputBase2>> { To = new VisualBasicReference<List<OutputBase2>> { ExpressionText = res.Name }, Value = new VisualBasicValue<List<OutputBase2>>("New List(Of OutputBase2)") });
        Activity act = getActivity(builder);

        var res2 = WorkflowInvoker.Invoke(act);
    }

    string getXamlStringFromActivityBuilder(ActivityBuilder activityBuilder)
    {
        string xamlString;
        StringBuilder stringBuilder = new StringBuilder();
        System.IO.StringWriter stringWriter = new System.IO.StringWriter(stringBuilder);
        System.Xaml.XamlSchemaContext xamlSchemaContext = new System.Xaml.XamlSchemaContext();
        System.Xaml.XamlXmlWriter xamlXmlWriter = new System.Xaml.XamlXmlWriter(stringWriter, xamlSchemaContext);
        System.Xaml.XamlWriter xamlWriter = System.Activities.XamlIntegration.ActivityXamlServices.CreateBuilderWriter(xamlXmlWriter);
        System.Xaml.XamlServices.Save(xamlWriter, activityBuilder);
        xamlString = stringBuilder.ToString();
        return xamlString;
    }

    public Activity getActivity(ActivityBuilder t)
    {
        string xamlString = getXamlStringFromActivityBuilder(t);
        System.IO.StringReader stringReader = new System.IO.StringReader(xamlString);
        Activity activity = System.Activities.XamlIntegration.ActivityXamlServices.Load(stringReader);
        return activity;
    }
}

      

        
        
        
      

    

Thanks!