Cause: The autoresponder is not connected, the list ID is wrong, or there is a form submission issue.
Fix:
Go to Autoresponders and verify the connection is active.
Check that the List ID matches your autoresponder account exactly.
Go to the Lists tab and check for yellow or red status indicators on the affected funnel.
Test by subscribing yourself using a different email address (one not already on the list).
Check your autoresponder's dashboard to see if the subscriber appeared. Some services have a double opt-in process where the subscriber must confirm via email before appearing on the list.
If using AWeber, check your "Unconfirmed" subscribers list — the subscriber may be waiting for email confirmation.
Check the Debug Log in Settings for error messages.
Look for JavaScript errors on the funnel page by opening your browser's Developer Console (press F12).