How To Solve This Facebook's Like Wall Problem?

[samsons17]

Hi I am creating a facebook like wall system.And at this point,my problem is I cant
get the wall writing back the "Whats on your mind?" in the textarea after a message has been post.

And this is the javascript for the wall :

var searchLabel = $('#tab1 form label').remove().text();
	  $('#message_wall').addClass('placeholder').val(searchLabel).focus(function() {
	    if (this.value == searchLabel) {
	      $(this).removeClass('placeholder').val('');
	    };
	  }).blur(function() {
	    if (this.value == '') {
	      $(this).addClass('placeholder').val(searchLabel);
	    };
	  });
	  $('#tab1 form').submit(function() {
	    if ($('#message_wall').val() == searchLabel) {
	      $('#message_wall').val('');
	    }
	  });

And the html code is here:

<FORM NAME="message_wall" ACTION="" METHOD="">
    	<label for="message_wall">What's On Your Mind?</label> 
                <textarea rows="3" name="S1" cols="104" id="message_wall" name="message_wall" value="message_wall"></textarea>
                <ul id="media">
                	<li><img src="images/link.png"> Link</li>
                	<li><img src="images/pictures.png"> Photo</li>
                	<li><img src="images/video.png"> Video</li>
                	<li><img src="images/audio.png"> Audio</li>
                </ul>
                <button type="submit" id="post-to-desk">Post to Desk</button>
                </FORM>

Help me please..Thank You :)