Contact Team Import

I'm trying to update contacts, specifically their contact teams. I go to import: contact team: and choose Don't Import Duplicate Records, Don't Create New Record, and Don't Import Field Value. I then map all the required fields, but I find error when mapping the Sign-In ID. I'm assuming that by using my Sign-In ID, it will update the contact team to wipe out all others and just list me as the owner. Is this correct? I keep running into error during import on this field.