Page.IsValid returning True, even though it isn't

I have a form onto which I add programatically several controls. This includes Text Boxes, Validators, etc.  Here is a section of code that does that adds the controls (AL is a PlaceHolder.  RS is a DataReader):
      AL.Controls.Add(New LiteralControl("<tr>" & vbCRLF))
      AL.Controls.Add(New LiteralControl("   <td align='right' valign='top'>First Name</td>" & vbCRLF))
      AL.Controls.Add(New LiteralControl("   <td>" & vbCRLF))
      TB = New TextBox
      TB.id = "AdvisorFirstName" & RS("ID").ToString
      TB.columns = 20
      TB.maxlength = 25
      TB.Text = RS("FirstName").ToString
  ...