Adding validation controls programmatically

[D Sheldon]

I am creating a server control that adds web controls (i.e. textboxes, etc) to a form. I use HtmlTable to build the table and insert the controls. Now I want to add validators to the textbox. Here is the code that I am using:

bool lastnamerequired=false;
public bool LastNameRequired
{
get{return lastnamerequired;}
set{lastnamerequired = value;}
}

if(lastnamerequired)
{
System.Web.UI.WebControls.RequiredFieldValidator rfv = new RequiredFieldValidator();
rfv.ControlToValidate = "sFirstName";
rfv.Display = ValidatorDisplay.Dynamic;
rfv.Text = "";
rfv.ErrorMessage = "Required";
rfv.EnableClientScript = true;
rfv.ID = "rfvFirstName";
td.Controls.Add(rfv);
}

This code seems to only add the word "Required" to my form when rendered. It's not dynamic nor does it go away when the field is valid.

Any ideas?