Servercontrols - Creating An Inherited Button That Can Cancel A Submit ?

There are no errors with my Javascript. The Javascript returns false, and the form is submitted. Additionally when setting UseSubmitBehavior to false the form still submits. What am I missing to prevent the form from being submitted?

// DerivedButton.cs
public class DerivedButton : System.Web.UI.WebControls.Button
{
public DerivedButton2()
: base()
{
this.OnClientClick = "DerivedButton_OnClick()";
//this.UseSubmitBehavior = false;
}
protected override void OnPreRender(EventArgs e)
{
base.OnPreRender(e);
string resourceName = "MyControls.DerivedButton.js";

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