If you used a widget to add the logo to the menu, you need to follow the correct code structure:
<div id="s5_logo_wrap" class="s5_logo s5_logo_css">
<img alt="logo" src="http://wp.b73.dk/wp-content/uploads/2016/03/cropped-B73-slagelselogosort-kopi-e1463997398230.jpg" onclick="window.document.location.href='http://wp.b73.dk/'">
<div style="clear:both;" />
If you didn't use a widget, then most of that code should be there automatically, but it appears that it's missing; did you edit anything in the index.php file of the theme?