Pop Up! Create a single popover for multisite

Hi,

I'm trying to set up one single popover which shows up on all the subdomains in my network install - and control the behavior of it globally. My goal is to have this one popover show up, but not show up as the user goes from subdomain to subdomain.

Problem - I can't get a popover to show up on any subdomains but my top level domain.

I've added the following to my wpconfig file as in the use instructions, and tried the plugin just activated on my TLD, then network activated. Not working.

define(‘PO_GLOBAL’, true);

Any help?