Zoho CRM Plug in for Outlook not always syncing

Zoho CRM Plug in for Outlook not always syncing

Hello - I have uninstalled and reinstalled Zoho CRM for Outlook Add in but I still have the problem where my assistant enters in a event for me in Zoho and most times it updates in my outlook but sometimes it doesn't and as a result I have not turned up to a couple of important events.  Can you help?

Thanks 
Amanda