I used UCI and family name (only). Not in capital letters.How did you link?
Using family name, given nane?
Did you write in all capital letter?
In my case, principal applicant does not have family name.
In your case, you may try to type PA's given name into the family name field as the instructions suggest.
Full name
Type your family name (surname) exactly as shown on your passport or travel document (even if the name is misspelled). Do not use initials.
Note: If you do not have a family name on your passport or travel document, enter all your given names here and leave the given name field blank.
Type all of your given names (first, second, or more) exactly as shown on your passport or travel document (even if the name is misspelled). Do not use initials.
Note: If you do not have a given name on your passport or travel document, leave this field blank. Do not enter “*”, “Not applicable” or “NA”.