Looping over birthdays does not work

In KWGT 3.57b121814 Pro, I am trying to loop over the birthday entries in a calendar using

[c=#aaffffff]$fl(1, ci(acount, a0d, "Contact birthdays"), "i+1", ci(title, "i-1", a0d, "Contact birthdays"), "

The loop is run the correct number of times, if there is one birthday, I get one line of output, with two two etc, but the "title" is always birthday index 0.

If I change the part in bold to 1, I get the second entry corresponding to the number of birthdays on that day.

What I am doing wrong with the for loop?