I am trying to use CKEditor in a Ajax Tab, but the toolbar doesn't show up

I added this to Web.config `<add tagPrefix="CKEditor" assembly="CKEditor.NET" namespace="CKEditor.NET"/>`

and this `<CKEditor:CKEditorControl ID="CKEditorControl1" runat="server" Toolbar=""></CKEditor:CKEditorControl>` into my webpage.

Any suggestions?
Thanks.