I'm e-filing 2021 form 3568 but it gets rejected with the following error:

For each Form 3568 present at least one corresponding CA-Binary Attachment document (PDF) with (AttachmentDescription) of 'IdentificacionDocument' must be attached.

I'm sending 2 attachments as follows:

#   Type         Form/Schedule and Description
1   Other       3568 Voter Reg ID
2   Other       3568 Birth Certificate

Any help please?