DataForm doesn't work in Silverlight 5 [closed]

Question

Reproduction:

1. Create a Silverlight project
2. Turn it to version 5
3. Add references to the Silverlight Toolkit (using NuGet or direct)
4. Add a DataForm to your page
5. This is the exception the DataForm constructor throws:
   {System.IO.FileNotFoundException: Could not load file or assembly 'System.Windows.Controls.Data.Input, Version=2.0.5.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified. [IO.FileName_Name] Arguments: System.Windows.Controls.Data.Input, Version=2.0.5.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35 Debugging resource strings are unavailable. Often the key and arguments provide sufficient information to diagnose the problem. See http://go.microsoft.com/fwlink/?linkid=106663&Version=5.0.60401.00&File=mscorlib.dll&Key=IO.FileName_Name at System.Windows.Controls.DataForm..ctor()}
6. Turn back to Silverlight 4
7. Now everything is cool again

Weird note: it does work in the VS/Exp. Blend 5 designers

Any ideas?? Workaround???