Importing tasks from Outlook and associating them with Contacts/Leads

Importing tasks from Outlook and associating them with Contacts/Leads

Prior to Zoho, I have been extensively using Outlook tasks to track customer interactions.
Now I need to migrate all Tasks from Outlook, so that they stay associated with appropriate Contacts or Leads. Otherwise I'm losing the history of my customer interactions.

I have exported Outlook's Contacts and Tasks modules into csv files. But when I try to upload Tasks to Zoho, the field Contact Name stays blank, even though I've set it to be equivalent to the "Contacts" field in Tasks (see scheenshot).

Please help.

Many thanks,
Anna