Required Field Validator Not Firing

protected void Page_Load(object sender, EventArgs e)
{
    Validate();
}

ScriptManager.RegisterStartupScript(this, GetType(), "js" + myTextBox.ClientID,
  "ValidatorHookupEvent(document.getElementById("" + myTextBox.ClientID +
  ""), "onblur", "ValidatorOnChange(event);");", true);

function blurred(sender) {
	var validator = sender.Validators[0]
	validator.evaluationfunction(validator);
}

<asp:TextBox runat="server" ID="txt" onBlur="blurred(this)"></asp:TextBox>