I used to have the same issue as you did; I could never seem to get it to work no matter how many times I followed it. Eventually I decided to read it word-for-word without following with a packet of cards and I realized I was reading it wrongly before -- I had apparently missed some small key details.
In short, it just takes a clear head and some careful reading. It may also be of help to you to use the cards pictured in the illustrations, and of course be sure that you are dealing the correct number of cards, etc. - either way, have fun with this one as it's a wonderful effect.
Take care,
Jordan
P.S. Just for a quick crediting issue, it's actually called the "
Packet Lie Detector #2".