With an identity of (-1,1), -1, -2 and -3 is just not the possible output.
The first record that goes in will have -1. Next would be -1 + 1 = 0. Finally, we would have 0 + 1 = 1.
It's probably just a typo, and I am sure the moderators will take a look and award the points.
The points not being awarded is a typical drawback with the automated evaluation systems - after all, all automation works on GIGO. If there was an error in framing the question, there's bound to be an error in the evaluation. Just another example of why automation should not be allowed work without supervision 🙂