/**
  * Returns the default image or a dummy one if it does not exists.
  * @return String
  */
 function DefaultImage()
 {
     if ($this->DefaultProductImageID) {
         if ($defaultImage = $this->DefaultProductImage()) {
             if ($defaultImage->exists()) {
                 return $defaultImage;
             }
         }
     }
     $obj = Product_Image::create();
     $obj->Link = $this->DefaultImageLink();
     $obj->URL = $this->DefaultImageLink();
     return $obj;
 }