CSS centering of an image not working
===

I'm trying to center an image (forces.png) horizontally using margin-left and margin-right auto but the image remains left-aligned. My site is http://goo.gl/cHO1u
What's wrong with the code I'm using? Thanks

HTML:

    <div class="section" id="presentation">
    <div id="presentation-highlevel">
    <p>NOTRE ENTREPRISE</p>
    <p>ddfdsfdsfdsfdsjfl dfljdsfdsfjdsjfdlksj dfljdslfjldsjflkdsjflsjfdls ldf,dlsmjfdsjfsdmfjdmsjfms dfmdsfjmdsjfmdsjfmdsjfdlms mkdfmksdmfkdmsfkdsfdsmfkmldskf dfmdmkfmdkfmdlskf dfkdmfkdmkfmdskf dfmkdsmfkdsmkfmdskfdms dskfdsmkfdsmkfmdsfkd </p>
    </div>
    <div id="presentation-highlights"><img src="images/forces.png" alt="Picture" /></div>
    </div><!--END page1-->

CSS:

    #presentation
    {
    	height:1300px;
    	background:#afc9ff; 
      background: url(../images/norway-landscape60.jpg) no-repeat center fixed; 
      -webkit-background-size: cover; /* pour Chrome et Safari */
      -moz-background-size: cover; /* pour Firefox */
      -o-background-size: cover; /* pour Opera */
      background-size: cover; /* version standardisée */
    }
    
    #presentation-highlights
    
    {
    width: 100%;
    display: block;
    margin-left:auto;
    margin-right:auto;
    }

