[fafner]

Yes, that's truly annoying. I have a few code examples that are complete but it refuses to accept them without giving any reason. If I try to step forward it says I have to go back.

Also in the first example it complained when I was using Math.round for the index calculation and only wanted to accept Math.floor. (although not applicable in this case, I think Math.floor is not the best choice since it won't behave like ints in negative cases)