mailchimp button missing from TinyMCE

Hi,

I am trying to use the mailchimp plugin with the popup pro as per the instructions here:

https://premium.wpmudev.org/blog/how-to-create-an-awesome-newsletter-signup-popup-for-your-wordpress-site/

however i seem to be missing the mailchimp button in the TinyMCE editor. any ideas?

I have network enabled the mailchimp plugin. this is a multisite site.