Header image not visible in IE

Dear Fooks,

I am using a header image which does not show up in IE unfortunately.
It does show in Firefox. I have checked discussions here but the image is RGB already, 8 bits so i don’t think thats the problem here..
site is https://www.portmantoo.nl and the css for header now reads the following:

#header div {padding:0;margin:0;width:100%;height:100%;}
#header{

width:3484px;
height:154px;
background: url(img/mini_icons2/logo.jpg)top left no-repeat;
margin-bottom:0.35em;

}

and my header php reads the following :

<div id="wrapper" class="hfeed">

	<div id="header">

<a href="https://www.portmantoo.nl"><div></div></a>

</div>

	<div id="access">
		<?php sandbox_globalnav() ?>
	</div><!-- #access -->

now the click does work in IE, only the image is not visible ! Hope someone can help me out?
Thanks!