Thank you for your feedback and problems details.
I have just try to DW PromoBar.
And, I think maybe that DW PromoBar is only assigned to Administrator is cause for your problems.
If you want to change the user role, please see the it file of dw-pomobar-options.php on line 8. add_submenu_page('options-general.php', 'DW PromoBar', 'DW PromoBar', 'administrator', 'dw_promobar', 'dwpb_settings_page');
(I try to change the administrator to edit_posts)