From what I just read on Tetra's website, I strongly suspect that Bactozym is just like the other "bacteria in a bottle" products and is on no use in cycling a tank. Actually, as sinistral mentioned, they don't even claim that it contains beneficial bacteria. They just say that it "has a unique two-way action which removes harmful waste and speeds up filter maturation. It stimulates the decomposition of uneaten fish food using naturally occurring enzymes, and it creates ideal conditions for the rapid development of filter bacteria" (quoted from their site). In actuality, the only thing required to "create the ideal conditions" for bacteria development is to add an ammonia source, raise the temperature and provide plenty of aeration. Maybe their product does contain ammonia. WH\hy don't you dose a 5 gallon bucket of tap water and test it to see what it shows.
In any case, there is no reason you should have nitrite that high if you have only added a few fish flakes unless the product indeed introduced ammonia and nitrite into the tank. What is you ammonia and nitrite reading? It will help us to figure out what is going on.