RequiredFieldValidator not working in custom control

I am trying to create a custom control that is a TextBox with a RequiredFieldValidator.  The RequiredFieldValidator is to display a small image when the TextBox is empty.  When the page loads the small image is already being displayed.  Entering a value in the TextBox is not causing the small image to disappear.  I don't think the RequiredFieldValidator is being properly linked to the TextBox.  Below is the code that is rendering the controls.  Any information that can shed some light on this problem would be very helpful.


protected override void RenderContents(HtmlTextWriter output)
        {
            TextBox t = new TextBox();
            RequiredFieldValidator r = new RequiredFieldValidator();
            Image i = new Image();

            //Set textbox properties
            t.Text = Text;
            t.ID = TextBoxID;  //TextBoxID is a property defined elsewhere in the class

            //Set image properties
            i.ID = "img" + TextBoxID;
            i.ImageUrl = Page.ClientScript.GetWebResourceUrl(this.GetType(), "AHS.HealthTrackWeb.UI.images.Error.png");
            i.AlternateText = ErrorMessage;  //ErrorMessage is a property defined elsewhere in the class
            i.Attributes.Add("style", "margin: 2px 2px 0 2px;");

            //Set validator properties
            r.ID = "rfv" + ID;
            r.SetFocusOnError = true;
            r.Display = Display;  //Display is a property defined elsewhere in the class
            r.EnableClientScript = true;
            //r.ErrorMessage = ErrorMessage;  //ErrorMessage is a property defined elsewhere in the class
            r.Controls.Add(i);
            r.ControlToValidate = t.ID;
           
            //Output results
            t.RenderControl(output);
            r.RenderControl(output);
           
        }