Email history not appearing under Contact's info

Email history not appearing under Contact's info

I am using Zoho as our company's email server, and using IMAP with Outlook or iPad email for my email client.  Some of my colleagues can see the "received" emails under each of their Contact's info in CRM, however I cannot see any emails, it just says "No Records Found". What do I need to do to be able to see the email history for each contact in CRM?