Error #1452 - Issue with adding or updating a child row

[JlarBo3]

I am trying to connect two tables in my created database. However, I am getting the error #1452 - Cannot add or update a child row. Interestingly, I can establish the fk-pk relationship while the table is empty, but when I transfer data to the table via CSV, I encounter an error. When I first establish the relationships and then try to import the data, I get an insertion error. What could be the reason for this?