CDATA Excel Add-in requires primary key fields for updating rows, How to set?

CDATA Excel Add-in requires primary key fields for updating rows, How to set?

Hi 

I use the CDATA.com excel add-in for ZOHO CRM, but am unable to update any table, because of missing primary key fields. Neither build-in fields nor custom autoimcrement fields are set to "primary key" in the database scheme. How can I achieve this? 

Cheers

Michael