Ultimate Branding Error Message

Why am I getting the error message below instead of the appropriate image on the login form?

Warning: getimagesize(http://www.mylifescene.net/wp-content/uploads/2015/09/MyLS_login_logo.png): failed to open stream: HTTP request failed! HTTP/1.1 503 Service Unavailable in /home/m796mls30pfhius/public_html/wp-content/plugins/ultimate-branding/ultimate-branding-files/modules/login-image.php on line 121