3
           
            
                
     
    
    solved it on my own..
here is the corrected code should anyone care to know.
$xComics = New xComics();
// url: 
http://www.tundracomics.com/strips/2007-2-15.gif$url_to_image = $xComics->build_image_url('1', 'tn');
$url_to_image = "http://www.tundracomics.com/strips/".date('Y-n-j').".gif";
if(!$xComics->exists_image($url_to_image))
{
 # set picture to two days ago (sometimes yesterday does not show)
 unset($url_to_image);
 $twodaysago = date('Y-n-j', mktime(0, 0, 0, date("m"), date("d")-2, date("Y")));
 $url_to_image = "http://www.tundracomics.com/strips/". $twodaysago .".gif";
 #$xComics->back_in_time('4', '2', 'tn');
}