Mailchimp subscribtion field

Hello i have a site in Drupal 8 and the mailchimmodule all is set up and the normal subscribtion form works k. But when i add a mailchimpsubscribtion field to the Drupal inbuilt contactform it let me fill and send the form but when i click the checkbox that is configured to subscribe in this form i get in the submisiion Invalid email configuration and the sender is not subscribed. Would be really glad if somebody can help Thank you Susanne