Can't set up Pop up Pro for a specific referrer

I have set up Pop Up Pro on my site, it works when testing in various display conditions.

But the one we need does not work, display “by a specific referrer”.

We want visitors that WE send to our site through newsletter to see a special popup. The link to our site that they click in the newsletter is something like…. , and so in the displaying conditions I entered “”.

But nothing will happen when I access the site through such a link in a test bowser. Again, the plugin works with other rules, but not with the referral rule.

Could the reason be that the referral URL is the same domain as the site itself? (I use a subdomain as referral link, though…:wink:

Hope you can help me!