Thanks for clarification, Chrono79!
Now test #2 is gone (I dunno how and where) and I change my solution logic for test #1. It works :-)

Not a kata issue, wrong answer subtracts 1, for the first one 7 is ok as expected answer, 0 - 1 + 4 + 4 == 7, the second one does seem wrong, but I checked the control function for Ruby and it would expect 3 for that test too, are you sure of that test?

There are some incorrect tests in the kata, for example:
checkExam(["b", "a", "c", "b"], ["", "b", "c", "b"]) # test expect 7, but correct answer 8 (0-1(→0)+4+4)
checkExam(["c", "d", "a", "a"], ["", "", "a", "c"]) # test expect 2, but correct answer 3 (0+0+4-1)

wonderful and clear decision, great!