Open each unmatched record within The Education Edge, and select a country on the Bio 1 tab for the address. The country selected then determines the character length of the ZIP/Postcode.

We have a student record with a United States address and 5-digit zip code. However, the County selected was blank. We select United States and Save and Close. We go back to Link records with The Raiser's Edge, and click Add All Unmatched Records. We are now able to create a matching record, and then link the records.