Having problem with add subscriber, please try again later.

Hi, thanks for a great plugin.

I can’t add single subscribers or import a list of subscribers, I get the following error:

“Having problem with add subscriber, please try again later.”

I’ve disabled all plugins and only have WP-SMS active, and I still have the issue.

I then tried a default WP theme, and I still have the problem.

Any ideas?

The page I need help with: [log in to see the link]