TSImport Client Information Failing

I'm trying to use TSImport to add some new client/matters to Timeslips. I've got all the fields mapped and I can see the data. However, when I try to import it fails with no explanation.

I'm wondering if there are some 'have to' fields Timeslips needs to import client information, but I'm not sure which ones. Or I suppose it could be another issue, but I'm not sure since there are no error codes.

Any thoughts?

Thanks