I set this property in the page load event...but no luck. My example is below...can you tell me what you did to make it work?

Private Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)

  If Me.ModalFrame.Visible = True Then
    Return
  End If

  Me.Suggestions.Attributes.Add("onChange", "javascript: changeWord(this);")
  Me.SpellingBody.Attributes.Add("onLoad", "javascript: initialize();")

  Me.SpellChecker.IgnoreHtml = True

  Me.LoadValues()

  Select Case Me.SpellMode.Value
     Case "start"

      Me.EnableButtons()

      Me.SpellChecker.SpellCheck()
    Case "suggest"
      Me.EnableButtons()
    Case Else
      Me.SpellChecker.DisableButtons()
  End Select

End Sub