Sent emails not showing in details of contactperson in CRM

Sent emails not showing in details of contactperson in CRM

We made this setup:
  • Zoho Mail add-on installed.
  • ´Emails´ tab activated in Zoho CRM
  • Syncing emails with our Google Apps account through the filter setup as described.
However,

Emails sent to a contact person, sent from the email tab or sent from my Google Apps account (supposedly syncing with Zoho Email through the ´sent emails filter´ I set up following the wiki), will all not show up under the ´Emails´ details section of the contactperson in CRM. 

Help, please.

Regards,

Jeroen