Find a div in Callback string

Find a div in Callback string

Hi folks,
 
I'm starting with jQuery (and I'm not very familiar with Javascript). It's probably an easy question but strangely enough I couldn't find anything that could help me solving my problem :
 
I have to get the status of a server via SSI command (<!--#echo var="myVar" -->). In my callback, I can display the whole webpage without problem. I can also see the relayDisplay div filled with my answer. Great!
 
But I want to extract it from that string. Tried with find and other functions, selectors... but I just can get undefined or Object not defined or null or [blank] or ...
 
  1.   $(document).ready(function(){
         function changeStatus(string)
         {
          //alert( string ) ;
          alert( $(string).find("#relayDisplay").html() ) ;
         }
         
         $("button").click(function(){$.get("http://192.168.254.254/index.html?cmd=myCmd", function(result){ changeStatus(result) ; }, "html" );
          });     
        });
       </script>
       <title>Test</title>  
     </head>                             
     
     <body>
            <div id="relayDisplay"><!--#echo var="myVar" --></div>
            <button>Change Content</button>
     </body>
    </html>

















Thank you in advance for your help!