Sorry to hear it - yeah, you have to keep it out of the red phase for about two minutes, so keeping it in the yellow is fine too. If you go into the red, it just pauses the timer until you get back into the green again.
Thanks for the feedback though, I might upload a patch later that makes it a bit easier. Let me know how you get on.
Edit: I've uploaded a patch that should make it easier and explain how it works a bit better. It should be a lot easier to get out of the red now too.