Help with homing missile I have one part working

Making a scrolling space shooting video game in C# where the player will fight one on one with their opponent. I was able to figure out how to make the missile go up if the opponent was above the player. But, I can't seem to make it work if the opponent is below or right infront of the player. Can someone help me? I know the answer is right under my nose.

The function below handles the movement of the missile

 void movemissile()
        {
            foreach (Control y in this.Controls)
            {
                if (y is PictureBox && y.Tag == "missile") 
                {

                    //y.Left += 100;//x.Top -= 10;
                    if (y.Left > enemy.Left)//<100
                    {
                        y.Left += 10;
                        //this.Controls.Remove(y);
                    }

                    //plyer missile goes up if opponent is above
                    if (y.Top > enemy.Top)
                    {
                        y.Left += 10;
                        y.Top -= 20;
                        y.Left += 10;
                        //this.Controls.Remove(y);
                    }
                    y.Left += 100;//x.Top -= 10;
                    if (y.Top > enemy.Left)//<100
                    { 
                        this.Controls.Remove(y);
                    }
                }
            }
        }

        This function handles drawing the missile of the player for the game.
                void Missile()
        {
            PictureBox m = new PictureBox();
            m.SizeMode = PictureBoxSizeMode.AutoSize;
            m.Image = Properties.Resources.Missile1;
            m.BackColor = System.Drawing.Color.Transparent;
            m.Tag = "missile";
            m.Left = Player.Left + 100;//moves bullet left or right
            m.Top = Player.Top + 55;//55 is perfect
            this.Controls.Add(m);
            m.BringToFront();
        }