Tree of BST - the algorithm to remove an item

[Andrzej Sydor]

I have such an algorithm (inspired from a book about algorithms Cormen):

   public void tree_delete(Node D, Node v) {
        Node y = null;
        Node x = null;
        if (v.left_son == null || v.right_son == null) {
            y = v;
        } else {
            y = tree_next(v);
        }
        if (y.left_son != null) {
            x = y.left_son;
        } else {
            x = y.right_son;
        }
        if (x != null) {
            x.rodzic = y.rodzic;
        }
        if (y == null) {
            D.korzen = x;
        } else {
            if (y == y.rodzic.left_son) {
                y.rodzic.left_son = x;
            } else {
                y.rodzic.right_son = x;
            }
            if (y != v) {
                v.wartosc = y.wartosc;
            }
 }
    }
       

Does anyone can tell me, why is not working properly?
And how to do that work?

The problem is the removal of the item to the parent and two children (in other cases more work):
that is, it looks something like this:

1
  3
 2 4

In this example, remove an item '3 ', and removed the link but I'm losing, that is, if it looks like this:

1
 
 2 4

instead of

1
  4
 2

What this is wrong?