Margin-top not working
===

When I use the margin-left it works. But the margin-top does not work. Anyone know why the on does work and the other doesn't?

Html code

    <div id="footer"> <!-- BEGIN FOOTER -->
	<p class="copyright"> Copyright © </p>
	</div> <!-- END FOOTER -->
Css

    #footer {
	
	background-image: url(../website/images/footer.png);
	width: 1200px;
	height: 100px;
	
	}
	
    p.copyright {
	
	margin-top: 10px;
	margin-left: 120px;
	
	}