Programmatically adding validation control to asp.net page

I am trying to add a required fields validator programmatically in asp.net. But I get the following error message - Control 'req2' of type 'RequiredFieldValidator' must be placed inside a form tag with runat=server

The c# code i have used is below -

protected void Page_Load(object sender, EventArgs e)
    {
        RequiredFieldValidator rv = new RequiredFieldValidator();
        rv.ID = "req2";
        rv.ControlToValidate = "TextBox2";
     开发者_JAVA百科   rv.ErrorMessage = "Data Required";
        this.Controls.Add(rv);
    }

Could someone tell me whats gone wrong here?

Thanks for sharing your valuable time.

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Try adding the control to the Form of the page. The reason for this is that you need to add this type of controls to a form.

this.Form.Controls.Add(rv);