* Verify the /cache/ folder in the plugin if it's readable/writable (try 0644 and if 0644 don't work try also 0755)
* Don't leave empty options in the administration Appaerence > modern advertise, "width of the left and right div" (expressed in pixel but add only the decimal value without "px" @ its ending). It's the same for width of your theme (and your theme must be a "column central theme" and you must add only the width of this main column with the sidebar).
* After, your background must be more largest then your theme to appears.
If you put here directly a link to your site, we would save time to view if it's a css problem for your theme (with F12 button) or a bad configuration from options in admin or a real problem from plugin.
* If you don't use a modern browser (min IE9) and others (Chrome, Firefox, Opera), the plugin work only with the main modern browser.
* If items don't appears in a list in Appareance > modern advertise (and below options), the problem comes from: you leave some inputs blank. Don't leave blank any inputs for each entries (or use simple css hack with "#" for some entries like url).