Import CSV

I'm trying to import properties via CSV.

First I exported successfully a couple of properties via the Export CSV function.

I use this CSV file to add another record and then go to
Other -> CSV Import
where I select the same CSV form that I used for the export. Then I click the Button
Import CSV
which brings me to
Step 1: Select CSV file
I select my CSV file which differs only in a new record from the previously exported version.
If I then press
Import CSV (same name of button but first in the list)
again I come to a screen (see attached)

that looks something is missing and the import did not take place.

What am I missing?

PS: XML export and import works fine. So my system appears to be running ok.