I'm trying to recall the buttons I created and position them on arrays that hold its location but FindControl gives Error.

```
 'Form1' does not contain a definition for 'FindControl' and no extension method 
 'FindControl' accepting a first argument of type 'Form1' could be found (are you missing
 a using directive or an assembly reference?)   

```

My code is under a timer1.

```
    private void timer1_Tick(object sender, EventArgs e)
    {
        ...
        if ...
        {
            ...
            Button btn = new Button();
            {
                btn.Name = "Btn-" + tail.ToString();
                btn.Height = 10;
                btn.Width = 10;
                btn.Tag = tail+1;
                btn.Location = new Point((stailX[1]-1)*10, (stailY[1] - 1) * 10);
            }
            this.Controls.Add(btn);
        }
        ...
        for (int i = 1; i <= tail; i++)
        {
            ((Button)this.FindControl("Btn-" + tail.ToString())).Location = new Point((stailX[i] - 1) * 10, (stailY[i] - 1) * 10);
        }

    }

```

I've omitted parts of code not important. Please help.