C++ :: Unable To See Enclosed Private Class

I have a class (Quadtree) and three inner class inside (Node, Inner and Leaf). Inner and Leaf inherit from Node.

I have a function in the private scope of Quadtree.

All these are located in fun.h .

Then, in fun.cpp, I am implementing the function (which is named foo <- what a prototype name!), which takes as argument a pointer to an Inner object. Inner seems unable to be resolved however!

fun.h Code: class Quadtree {
private:
class Node{
public:
Node() { std::cout << "Node
"; }
};
class Inner : public Node {
public:
Inner() { std::cout << "Inner

[code]....