You have to cast the elements of your ArrayList. public static void PrintValues( IEnumerable myList ) { System.Collections.IEnumerator myEnumerator = myList.GetEnumerator(); while ( myEnumerator.MoveNext() ) { Console.Write( "\t{0}", ((Node) myEnumerator.Current).Key.ToString()); Console.WriteLine(); } }

Why are you trying to override this? If you're just using a SortedList, you just use it like the code example I gave. If you do want to extend a class, you only have to override abstract methods, and override other methods and properties as you need to. In this case, though, it's seems like you don't need to. Besides, when you declare an indexer for a class in C#, you use the following syntax: public object this[int index] { get { return internalList[index]; } set { internalList[index] = value; } } Read the .NET Framework SDK for more information, especially since your new. Specifically, see the Visual C# Language[^] topic. Microsoft MVP, Visual C# My Articles