Methods in nested interfaces do not return values

[aloneguid]

   public interface ICallableConfig
   {
      string GetFirst(string sectionName, string key);

      [Option(Alias = "A")]
      string GetSecond(string sectionName);

      [Option(DefaultValue = "n/a")]
      string GetThird(string name);

      void SetFirst(string name);

      INestedCallableConfig Nested { get; }
   }

   public interface INestedCallableConfig
   {
      string GetNested(string sectionName);
   }

calling _config.Nested.GetNested("section"); does not return a proper value.