MailChimp / Forms App double-duty and optional opt-in

Thanks Drew. The form submits successfully to the Forms App, but not to the Mailchimp app or the Mailchimp website, where the entry isn't added. I can't find what I'm doing wrong in the code.

Here's my form (with all the Foundation layout code stripped out for easier reading).

<perch:form id="contact" app="perch_mailchimp perch_forms" double-optin="false" send-welcome="false">

<perch:content id="intro" type="textarea" label="Form introduction" size="xs" editor="redactor" html="true" size="m" divider-before="Contact Form" />

<perch:error for="name" type="required">Please add your name</perch:error> <perch:input type="text" id="name" required="true" label="Name" placeholder="Your Name" mailer="NAME" />

<perch:error for="email" type="required">Please add your email address</perch:error> <perch:input type="text" id="email" required="true" label="Email" placeholder="Your Email" mailer="EMAIL" />

<perch:error for="phone" type="required">Please add your phone number</perch:error> <perch:input type="text" id="phone" required="true" label="Phone" placeholder="Your Phone" mailer="PHONE" />

<perch:error for="zip" type="required">Please add your zip code</perch:error> <perch:input type="text" id="zip" required="true" label="Zip Code" placeholder="Your Zip Code" mailer="ZIP" />

<perch:error for="subject" type="required">Please choose your subject</perch:error> <perch:input type="select" id="subject" options="Choose your subject...,Where to Buy, Product Usage, Interest in Selling Kellogg and/or G&B Organic Products, Rebates, Other" />

<perch:error for="message" type="required">Please add a message</perch:error> <perch:input type="textarea" id="message" required="true" label="Message" placeholder="Your Message" />

<perch:error for="message" type="required">Join our mailing list?</perch:error> <perch:input type="checkbox" value="1" id="confirm" mailer="confirm_subscribe" /> Would you like to join our mailing list?

                <div style="display:none;">
                    <perch:input type="text" id="chaff" antispam="honeypot" label="Leave this field blank." />
                </div>

                <div>
                    <perch:input type="submit" id="submit" value="Send" />
                </div>

                <perch:success>
                    <perch:content id="success" type="textarea" label="Thank you message" html="true" editor="redactor" size="m" />
                </perch:success>
        </perch:form>

So if I visit the page with the form the debug on, I see this:

Debug Message
SELECT * FROM perch2_pages WHERE pagePath='/contact/index.php' LIMIT 1
Using template: /templates/pages/attributes/default.html
Using sub-template: /templates/pages/attributes/seo.html
Using template: /templates/pages/attributes/default.html
Using sub-template: /templates/pages/attributes/seo.html
SELECT regionKey, regionHTML FROM perch2_content_regions WHERE regionPage='/contact/index.php' OR regionPage='*' ORDER BY regionPage DESC

If I submit the form on the page I see this:
SELECT DISTINCT settingID, settingValue FROM perch2_settings WHERE userID=0
SELECT * FROM perch2_forms WHERE formKey='contact' LIMIT 1
SELECT * FROM perch2_pages WHERE pagePath='/contact/' LIMIT 1
Checking Akismet for spam
Message is not spam
Message sent!
INSERT INTO perch2_forms_responses(responseJSON,formID,responseIP,responseSpamData) VALUES('{\"fields\":{\"name\":{\"attributes\":{\"type\":\"text\",\"id\":\"name\",\"required\":\"true\",\"label\":\"Name\",\"placeholder\":\"Your Name\",\"mailer\":\"NAME\"},\"value\":\"Franz Test 3\"},\"email\":{\"attributes\":{\"type\":\"text\",\"id\":\"email\",\"required\":\"true\",\"label\":\"Email\",\"placeholder\":\"Your Email\",\"mailer\":\"EMAIL\"},\"value\":\"franz3@copyanddesign.com\"},\"phone\":{\"attributes\":{\"type\":\"text\",\"id\":\"phone\",\"required\":\"true\",\"label\":\"Phone\",\"placeholder\":\"Your Phone\",\"mailer\":\"PHONE\"},\"value\":\"111-222-3333\"},\"zip\":{\"attributes\":{\"type\":\"text\",\"id\":\"zip\",\"required\":\"true\",\"label\":\"Zip Code\",\"placeholder\":\"Your Zip Code\",\"mailer\":\"ZIP\"},\"value\":\"90807\"},\"subject\":{\"attributes\":{\"type\":\"select\",\"id\":\"subject\",\"options\":\"Choose your subject...,Where to Buy, Product Usage, Interest in Selling Kellogg and\\/or G&B Organic Products, Rebates, Other\"},\"value\":\"Other\"},\"message\":{\"attributes\":{\"type\":\"textarea\",\"id\":\"message\",\"required\":\"true\",\"label\":\"Message\",\"placeholder\":\"Your Message\"},\"value\":\"Debug on, checked for opt-in\"},\"confirm\":{\"attributes\":{\"type\":\"checkbox\",\"value\":\"1\",\"id\":\"confirm\",\"mailer\":\"confirm_subscribe\"},\"value\":\"1\"}},\"files\":[],\"page\":\"\\/contact\\/\"}','1','71.189.216.125','{\"fields\":{\"honeypot\":\"\"},\"environment\":{\"PATH\":\"\\/sbin:\\/usr\\/sbin:\\/bin:\\/usr\\/bin\",\"PP_CUSTOM_PHP_INI\":\"\\/var\\/www\\/vhosts\\/system\\/kellogggarden.com\\/etc\\/php.ini\",\"PP_CUSTOM_PHP_CGI_INDEX\":\"fastcgi\",\"SCRIPT_NAME\":\"\\/contact\\/index.php\",\"REQUEST_URI\":\"\\/contact\\/\",\"QUERY_STRING\":\"\",\"REQUEST_METHOD\":\"POST\",\"SERVER_PROTOCOL\":\"HTTP\\/1.0\",\"GATEWAY_INTERFACE\":\"CGI\\/1.1\",\"REMOTE_PORT\":\"42427\",\"SCRIPT_FILENAME\":\"\\/var\\/www\\/vhosts\\/kellogggarden.com\\/httpdocs\\/contact\\/index.php\",\"SERVER_ADMIN\":\"root@y6vk-hs8n.accessdomain.com\",\"DOCUMENT_ROOT\":\"\\/var\\/www\\/vhosts\\/kellogggarden.com\\/httpdocs\",\"REMOTE_ADDR\":\"71.189.216.125\",\"SERVER_PORT\":\"80\",\"SERVER_ADDR\":\"72.47.233.152\",\"SERVER_NAME\":\"y6vk-hs8n.accessdomain.com\",\"SERVER_SOFTWARE\":\"Apache\",\"SERVER_SIGNATURE\":\"<address>Apache Server at y6vk-hs8n.accessdomain.com Port 80<\\/address>\\n\",\"HTTP_COOKIE\":\"cmsa=1; PHPSESSID=u8kskue3jiaf1k1sb5hflp40r0; __unam=3210271-14c902a4384-3d88c8c8-25; _ga=GA1.2.674700413.1428347830; _gat=1\",\"HTTP_DNT\":\"1\",\"HTTP_REFERER\":\"https:\\/\\/y6vk-hs8n.accessdomain.com\\/contact\\/\",\"HTTP_USER_AGENT\":\"Mozilla\\/5.0 (Macintosh; Intel Mac OS X 10_10_2) AppleWebKit\\/600.4.10 (KHTML, like Gecko) Version\\/8.0.4 Safari\\/600.4.10\",\"HTTP_ORIGIN\":\"https:\\/\\/y6vk-hs8n.accessdomain.com\",\"CONTENT_TYPE\":\"application\\/x-www-form-urlencoded\",\"HTTP_ACCEPT_LANGUAGE\":\"en-us\",\"HTTP_ACCEPT_ENCODING\":\"gzip, deflate\",\"HTTP_ACCEPT\":\"text\\/html,application\\/xhtml+xml,application\\/xml;q=0.9,*\\/*;q=0.8\",\"CONTENT_LENGTH\":\"267\",\"HTTP_CONNECTION\":\"close\",\"HTTP_X_ACCEL_INTERNAL\":\"\\/internal-nginx-static-location\",\"HTTP_X_FORWARDED_FOR\":\"71.189.216.125\",\"HTTP_X_REAL_IP\":\"71.189.216.125\",\"HTTP_HOST\":\"y6vk-hs8n.accessdomain.com\",\"UNIQUE_ID\":\"VSVzb0gv6ZgAADrdFIYAAAAB\",\"FCGI_ROLE\":\"RESPONDER\",\"PHP_SELF\":\"\\/contact\\/index.php\",\"REQUEST_TIME_FLOAT\":1428517743.5198,\"REQUEST_TIME\":1428517743}}')
SELECT * FROM perch2_forms_responses WHERE responseID='91' LIMIT 1
Logging resources for
No ids to log.
SELECT * FROM perch2_pages WHERE pagePath='/contact/index.php' LIMIT 1
Using template: /templates/pages/attributes/default.html
Using sub-template: /templates/pages/attributes/seo.html
Using template: /templates/pages/attributes/default.html
Using sub-template: /templates/pages/attributes/seo.html
SELECT regionKey, regionHTML FROM perch2_content_regions WHERE regionPage='/contact/index.php' OR regionPage='*' ORDER BY regionPage DESC
Array
(
    [type] => 8
    [message] => Trying to get property of non-object
    [file] => /var/www/vhosts/kellogggarden.com/httpdocs/perch/core/lib/api/PerchAPI_Base.class.php
    [line] => 19
)

Perch 2.8.2.