XamlTypeResolverProvider GetNamespaceOfPrefix needs to look also on ParentObject to find the XMLNS, because,

new XML Element are created for Example for Binding, wich are not yet in the XML Tree, when XamlTypeResolverProvider is used, but
the ParentObject Property is set!
With this Method you find the correct Namespace through the Tree

src/AddIns/DisplayBindings/WpfDesign/WpfDesign.XamlDom/Project/XamlTypeResolverProvider.cs

@@ -29,16 +29,32 @@ namespace ICSharpCode.WpfDesign.XamlDom
 		XmlElement ContainingElement{
 			get { return containingObject.XmlElement; }
 		}
+
+		private string GetNamespaceOfPrefix(string prefix)
+		{
+			var ns = ContainingElement.GetNamespaceOfPrefix(prefix);
+			if (!string.IsNullOrEmpty(ns))
+				return ns;
+			var obj = containingObject;
+			while (obj != null)
+			{
+				ns = obj.XmlElement.GetNamespaceOfPrefix(prefix);
+				if (!string.IsNullOrEmpty(ns))
+					return ns;
+				obj = obj.ParentObject;
+			}
+			return null;
+		}
 		
 		public Type Resolve(string typeName)
 		{
 			string typeNamespaceUri;
 			string typeLocalName;
 			if (typeName.Contains(":")) {
-				typeNamespaceUri = ContainingElement.GetNamespaceOfPrefix(typeName.Substring(0, typeName.IndexOf(':')));
+				typeNamespaceUri = GetNamespaceOfPrefix(typeName.Substring(0, typeName.IndexOf(':')));
 				typeLocalName = typeName.Substring(typeName.IndexOf(':') + 1);
 			} else {
-				typeNamespaceUri = ContainingElement.GetNamespaceOfPrefix("");
+				typeNamespaceUri = GetNamespaceOfPrefix("");
 				typeLocalName = typeName;
 			}
 			if (string.IsNullOrEmpty(typeNamespaceUri))