IXAmlTypeResolver.Resolve failing in Blend

Question

I'm attempting to do some type resolution inside of a WPF Markup Extension using the same namespace:StaticType.Property syntax that StaticExtension uses. The extension works fine at runtime and also in the Visual Studio designer, but it fails in Expression Blend. After some debugging I figured out that the failure occurs in a call to IXamlTypeResolver.Resolve().

// Parse Static=properties:Resources.HelloWorld like static resource
int index = this.Static.IndexOf('.');
if (index == -1)
    throw new ArgumentException(Resources.InvalidStaticBindingSyntax + ": " + 
                                this.Static);

// resolve properties:Resources
string typeName = this.Static.Substring(0, index);
IXamlTypeResolver service = _serviceProvider.GetService(typeof(IXamlTypeResolver))
                            as IXamlTypeResolver;

Type memberType = service.Resolve(typeName);

string propName = this.Static.Substring(index + 1);
localized = memberType.GetProperty(propName,
                       BindingFlags.Public | 
                       BindingFlags.Static | 
                       BindingFlags.FlattenHierarchy)
                       .GetValue(memberType, null);

The problem is the service.Resolve(typeName) which fails, but only in Blend.

Took a look at the StaticExtension with Reflector and the code MS is using doesn't look much different.

It looks like a security issue - but I've even tried to sign and GAC the assembly and it still fails exactly the same.

Stumped.