I can't see the toolbars in htmleditorextender

I have added the latest version of the AJax Control Toolkit and I am trying to add the htmleditor.  Any ideas?

I have already tried replacing script manager with toolscript manager.

Here is the code:

<asp:TextBox ID="txt_editor" runat="server" TextMode="MultiLine" Rows="5" Columns="10"></asp:TextBox>
<ajaxToolkit:HtmlEditorExtender runat="server" TargetControlID="txt_editor">

</ajaxToolkit:HtmlEditorExtender>