[Plugin: Custom Field Suite] display image

Hi guys
I created a field called “logo”, when I uploaded the image in each post, the value always return a value like “34”, it is not a URL.
I checked the field setting that I set return value is URL, but does not work.
and this is my code:
$cfs->get(‘logo’,$postid);

if I leave $postid empty, it is still not working.

http://wordpress.org/extend/plugins/custom-field-suite/