ClassNotFound exception for inner class

[hirop35]

I have been developing a binary search tree class using generics, and my class contains several Interfaces and inner classes, including a Tree node class, an interface for a callback (used by my iterators) an interface for a tree iterator, and several iterator classes that implement the tree iterator interface:

public abstract class BinaryTree<E> implements Tree<E> {

  BinaryTreeNode<E> root;
  TreeComparator compares;
  int numberOfNodes;
  int iType;

	    ...
	    ...
	    ...

  public interface TreeCallback<E> {
	public void visit( BinaryTreeNode<E> node, Object[] arr );
  }

  interface TreeIterator<E> {
	public void traverse( BinaryTreeNode<E> node );
  }
	
  public class InOrder<E> implements TreeIterator<E> {
	TreeCallback<E> callBack;
	Object[] objects;
		
	public InOrder( TreeCallback<E> callBack, Object[] arr  ) {
		this.callBack = callBack;
		objects = arr;
	}
		
	public void traverse( BinaryTreeNode<E> node ) {
			 
		if( node != null ) {
			traverse( node.leftChild );
			callBack.visit(node, null);
			traverse( node.rightChild );
		 }
	}
  }

   	    ...
	    ...
	    ...

  public void doTraversal( TreeCallback<E> callBack, Object[] arr) {
		
	switch( iType )
	{
		case IteratorType.INORDER:
			new InOrder<E>( callBack, arr ).traverse(root);

                          case ...
  			     ...
			     ...
	}

this code compiles fine and gives me no error (I am using eclipse Gallileo). However, when I run this program, at the point the InOrder class (TreeIterator) consturctor is first called:

 case IteratorType.INORDER:
	new InOrder<E>( callBack, arr ).traverse(root);

A ClassNotFoundException (arg0: myCollections/BinaryTree$InOrder) is thrown. The class file does in fact exist and is located inside the same bin folder as the enclosing class (which is instantiated without problem).

I am new to Java generics, but from what I've read, I thought that this problem might be related to the class parameters in some way - but I have rewritten the class as a non parameterized class and got the same error.

again, my class is on the same classpath as all of my other classes in the project, so it is clearly not a classpath issue. Somebody please help, I am at my wits end