Problem with adding banner to Digital Statement Theme

I am trying to add a banner to the Digital Statement Theme and I am not able to through the CSS no matter what I try. I want the banner to fill the entire blank space in the header and sitting behind the search box.

My site is: http://www.beyondmediaonline.com

This is the header code:

/*+++++++ HEADER+++++++*/
#header {display:block; width: 915px; height: 94px; margin: 0 auto;}
#logo {display: block; float:left; background:url(images/logo.gif) top left no-repeat; height: 94px; margin: 30px 0 0 0;}
#logo h1 a {padding: 10px 0 0 0; font-size: 24px; color: #666}
#searchbox { float:right; width: 200px; border: 1px solid #ccc; margin:30px 0 0 0;}
#searchbox #s { float: left; margin: 3px 0 0 5px; border: 0; width: 155px; background: none; color:#999999;}
#searchbox #go { float: right; border-left: 1px solid #ccc}

I have tried about everything I can think of even removing the #logo h1 line. The image path is correct.

Thanks