Microsoft.Xrm.Sdk.Workflow.Activities.Workflow throws exception in designer

Hi, 

I've created a new XAML Workflow library in a Microsoft Dynamics CRM 2011 Developer Toolkit 1.1 project and a new XAML Workflow Activity as described in Create and Deploy XAML Workflows Using the Developer Toolkit but dragging and dropping Workflow activity throws the System.IO.IOException: unable to locate the resource 'workflowdesigner.xaml' (I've transaleted description).

Where am I wrong?