Async CTP Framework IValueConverter problem

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C#

WPF

C#4.0

Dear All,

I face problem using IValueConverter in WPF project.
I have installed Async CTP frame work (V:3.0) with following detail

VS: 2010 SP1
Async CTP framework 3.0
.net farmework 4.0


Application is working well with async/await. Only issue i face when I use converter. I don't know what this issue is

I have imported AsyncCtpLibrary.dll and System.Threading.Tasks.Dataflow.dll.

Error that I face when i add reference of converter in xaml

Cannot find all types required by the 'async' modifier. Are you targeting the wrong framework version, or missing a reference to an assembly?

Predefined type 'System.Runtime.CompilerServices.IAsyncStateMachine' is not defined or imported


Is there any requirement for using converter

One thing again I am not going to upgrade to 4.5. and issue only found when use of any converter
Bellow is simple code for converter.

public class TriggerTypeConverter : IValueConverter
   {
       public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
       {
           if (value != null)
           {
               if (value.ToString().ToUpper().Equals("ADMN"))
               {
                   return "Admin Sync Trigger(s)";
               }
               else if (value.ToString().ToUpper().Equals("CMS"))
               {
                   return "CMS Trigger(s)";
               }
           }
           return null;
       }

and XAML where i reference converter (referenced namespace address is ok. so no issue with directive)

< xmlns:converter="clr-namespace:NFS.Admin.Converters" >

    <my1:UserControl.Resources>
        <converter:TriggerTypeConverter x:Key="triggerTypeConverter"/>
        <converter:EnableTypeConverter x:Key="enableTypeConverter"/>
    </my1:UserControl.Resources>