Unfortunately, there isn't much more information to go on to solve your issue.  If that is the default Poser background color then either the sphere is not present or invisible.  Those are features to check into relatively quickly.  Also, check if you need to load a background texture onto the sphere.  It would be unusual for the vendor not to provide a loaded image but things happen.  Going through the readme text provided on the webpage, I see no mention of a sky cube nor any prop associated with the background image.  That makes me believe that you may need to import the image to fill the background.