Like any routine, as people said above, nutrition and rest play a bigger role then the workout itself. 9 times out of 10 people don't get enough food or sleep. If you really aren't going WAY out of your way to eat and take in enough protein, then you probably aren't getting near enough. I think you would be suprised if someone fed you what you should really be eating during a day.
Even people who think they are eating enough are probably only about half way there. My friend thought he was getting enough protein and we looked at his diet. He was only gettinig about 70g of protein a day!!!! He thought he was getting more then enough. That was less then half of what he should have been getting. His calories were WAY off also. He was complaining he couldn't gain any weight or strength, hmm wonder why. Getting 8hrs good sleep is also very important. Some people think just because they aren't very tired, that they can go on 6hrs or so no problem. Well, your body is going to use its energy to keep you goinig and won't have much extra for repair.
I doubt that its the single factor program that is the problem. You should evaluate your diet and rest. You should also see if you are doing something wrong as far as intensity or exercises.