Help Understanding Zoho CRM and Outlook tool

Help Understanding Zoho CRM and Outlook tool

We are new to Zoho CRM and using the Outlook toolbar.  Several of us are testing the system.  I have uploaded part of our database to Zoho CRM and the synching works fine for me.  The other person is trying to synch and have the data from Zoho download to his Outlook.  He switches off between Zoho rules and Outlook rules but each time it tells him that there are no changes.  What are we doing wrong?  Can someone only upload/download contact that they enter into the system?  Please advise.  Thanks!