Unbounce not triggering addition of leads in Mailchimp list


Hi, I have followed all the instructions and videos but when I sign up in a form on my Unbounce landing page it doesn’t trigger the addition of the lead to my MailChimp list.

I do receive an email notification to say that the lead has been created in Unbounce from Unbounce, but it doesn’t trigger the MailChimp email form - I am expecting it to show the Opt-In signup form, but I don’t get this email.

Can anyone tell me what I’m missing please? Thanks. Aidan