Hi Robin,
Which of the snippets listed are you using? The top snippet is only for AJAX enabled forms which only exist in the premium version of the plugin.
If you want to track your form submissions using the lite version of the plugin, please use the bottom snippet or add your tracking code to the success message.
Example script (all form submissions)
<script type="text/javascript">
// find all mailchimp for wordpress forms
var forms = document.querySelectorAll('form.mc4wp-form, .mc4wp-form form');
// attach google analytics event to form submit event
for( var i = 0; i < forms.length; i++ ) {
forms[i].onsubmit = function() {
// analytics.js
ga('send', 'event', 'button', 'click', 'Sign-up form submission');
}
}
</script>
Example success message with tracking code
Thanks a lot, please check your inbox for a confirmation email! <script type="text/javascript">ga('send', 'event', 'button', 'click', 'Sign-up form submission');</script>
Hope that helps!