Migrate accounts and contacts through kingswaysoft

I am migrating accounts and contact from one CRM instance to another. In order to migrate account and associate related contacts to them, following are the steps performed:

1. Migrating account without primary account and primary contact Ids

2. Migrating contacts- using conditional split to see whether parent of the contact is Account or Contact record.

In 2nd step, I am migrating contacts directly if the parent is not a contact record. But if it is a contact, in this step contacts are migrated without parentcustomerid field.

The case where parent is not a contact, where complete contact records are migrated, i am getting an error saying 'parentcustomerid' should not be null. i.e the case where there's no parent record for the contact.

I tried ticking Ignore null valued fields, but no help. 

Please suggest.