It should work on all wood, or at least it has for me so far. You may have to play a little with the angle at which you hold your spine to the wood, and you're going to have to put a little strength behind it. Start with the spine perfectly perpendicular then cant the knife down very slightly. If that doesn't work, cant down a little more, etc. There should be a certain angle were it will shave real nice.
Also, be sure that your spine is nice and flat. Try scraping a Sharpie pen, you should be able to get nice little plastic curls if your spine is sharp enough.
Keep playing with it, you'll figure it out, if all else fails, get a cheap beater or kitchen knife and use the edge perpendicular just so you can see how the curls should be.
Also, maybe just try some different wood, but pine should be great though.
P.S. You may have problems if your knife is laminated or differentially heat treated. In other words, if your spine isn't as hard as your edge, it may dull too quickly to get any good shavings, and it won't be able to get sparks from the firesteel.
I sure hope you get it figured out, because it's a real joy to be able to start a fire with just your knife and a firesteel.