Unknown Toolbar Item "Undefined" in IE

FCKeditor is working fine in firefox. But in IE 6 I get this alert window each time the page loads. Here is my toolbar set:

FCKConfig.ToolbarSets["Default"] = [
['Source','-','Save','NewPage','Preview'],
['Cut','Copy','Paste','PasteText','PasteWord','-','Print',],
['Undo','Redo','-','Find','Replace','-','SelectAll','RemoveFormat'],
['Bold','Italic','Underline','StrikeThrough','-','Subscript','Superscript'],
['OrderedList','UnorderedList','-','Outdent','Indent'],
['JustifyLeft','JustifyCenter','JustifyRight','JustifyFull'],
['Link','Unlink'],
['Image','Table','Rule','Smiley','SpecialChar'],
['Style','FontFormat','FontName','FontSize'],
['TextColor','BGColor'],
['About']
] ;