Following this post: link text I'm trying to create an expression tree that references the property of a property. My code looks like this:

public interface IFoo
{
    void X {get;set;}
}

public interface IBar : IFoo
{
    void Y {get;set;}
}

public interface IFooBarContainer
{
    IBar Bar {get;set;}
}

public class Filterer
{
     //Where T = "IFooBarContainer"
     public IQueryable<T> Filter<T>(IEnumerable<T> collection)
     {
              var argument = Expression.Parameter(typeof (T), "item");

              //...

               //where propertyName = "IBar.X";
               PropertyOfProperty(argument, propertyName); 
     }

        private static MemberExpression PropertyOfProperty(Expression expr, string propertyName)
        {
            return propertyName.Split('.').Aggregate<string, MemberExpression>(null, (current, property) => Expression.Property(current ?? expr, property));
        }
}

I receive the exception:

System.ArgumentException: Instance property 'X' is not defined for type 'IBar'

ReSharper turned the code in the link above into the condensed statement in my example. Both forms of the method returned the same error.

If I reference IBar.Y the method does not fail.