Problem in Createing run time Button

Question

Hi
i have created button on run time and adding  some attributes and when i want to add post attribute at run time it added successfully but not working can any one tell how can i do this...?

        Button btn = new Button();

        btn.ID = "btn5";

        btn.Attributes.Add("runat", "server");

        btn.Attributes.Add("onclick", "pop('" + btn.ID + "')");

      //  btn.Attributes.Add("PostBackUrl", "~/Default2.aspx");

        btn.Text = "Test";

        this.form1.Controls.Add(btn);