You just found a bug!
Open wordpress-popular-posts.php using an editor such as Notepad or Dreamweaver, and change this code (around line 1021):
echo “<!– WordPress Popular Posts Plugin v”. $this->version .” [SC] [“.$shortcode_ops[‘range’].”] –>”.”\n”;
// is there a title defined by user?
if (!empty($header) && !empty($header_start) && !empty($header_end)) {
echo $header_start . $header . $header_end;
}
// print popular posts list
echo $this->get_popular_posts($shortcode_ops, false);
echo “<!– End WordPress Popular Posts Plugin v”. $this->version .” –>”.”\n”;
… into this:
$shortcode_content = “”;
$shortcode_content .= “<!– WordPress Popular Posts Plugin v”. $this->version .” [SC] [“.$shortcode_ops[‘range’].”] –>”.”\n”;
// is there a title defined by user?
if (!empty($header) && !empty($header_start) && !empty($header_end)) {
$shortcode_content .= $header_start . $header . $header_end;
}
// print popular posts list
$shortcode_content .= $this->get_popular_posts($shortcode_ops, false);
$shortcode_content .= “<!– End WordPress Popular Posts Plugin v”. $this->version .” –>”.”\n”;
return $shortcode_content;
That should fix it for the moment. I’ll include this patch on the next release of WordPress Popular Posts.