I often found that it wouldn't register my keystrokes. Perhaps it's because I type too quickly, and whenever I built up some speed it would fail to register one and I'd get backlogged again. You should include punctuation in what you're required to type; I spent a lot of time hitting punctuation marks before realizing I didn't need to, but it can be helpful to slow a typist down some... particularly your heavy use of quotation marks. I, personally, find those the hardest.
Anyway, my biggest problem is with the inability to keep up with my fast typing. I don't know where it started failing; I know that I never got up to speed, so maybe it was at 80wpm it failed, or maybe it was 100, but I'm sure that I made the keystrokes, and it happened many times.