First of all I would like to say Thank You to the author of this skin, it was very helpful for me.

But I faced to some problem using it yesterday. I see my portfolio page only in the admin panel, when I end the session, i see the page with a mistake :

Fatal error: Call to a member function get_url() on a non-object in ...../public_html/skins/stain_skin/_skin.class.php on line 1447.

Or (i tried it on another site) :

Fatal error: Call to a member function get_url() on boolean in ....../public_html/skins/stain_skin/_skin.class.php on line 1263.

These lines are both about the finding the url of the header image of the page, in header settings (line 1263) and search display options (line 1447) relatively :

$custom_css .= ".main_header{ background-image: url('".$bg_image_File->get_url()."') }";

$custom_css .= ".search_head{ background-image: url('".$bg_image_File1->get_url()."') }"

As I see, they are written with no mistakes. System parameters are all OK.

What is the kind of problem, can anybody promt how it should be solved ?
Thank you in advance.