Changing the CKEditor toolbar on the fly

Hi,
I am new to CKEditor. I am calling a java script method ('changeToolBar()') during the instanceReady of my CKEditor. In the changeToolBar() method, I am trying to change the toolbar but the toolbar is not getting changed. Any help is appreciated.

Here is my code:

<script type=\"text/javascript\">
 var oEditor = CKEDITOR.replace( ' sRTFName  ', 
    {  
      on : 
         {  
            instanceReady : function( ev ) 
               { 
                  changeToolBar(ev); 
               } 
         }
   });
   
function changeToolBar( editorInstance )
{
   if(mode == 2) // if mode is 2 then it is view only
   {      
       editorInstance.editor.config.toolbar = 'TAReadOnly';
       //toolbar TAReadOnly enables only maximize button
   }
   else{
      // code for edit mode.
   }
}   
</script>