It's hard to aim using the Lancet device.... Try just freehand poking the sweet spot. It's OK if you go all the way through so don't worry. Just put a cotton round or folded paper towels behind to protect your fingers.
If you aren't comfortable going freehand, I use the biggest setting on the lancet pen. You can lower as needed/necessary as he starts to bleed better. Janet is absolutely right in that you can aim better if you freehand poke, but I somehow haven't really gotten myself to try that.... which is really silly now that I think about it because after everything else I've done on this journey, freehand poking shouldn't be scary at all.
Start with the deepest setting and reduce as necessary. A cat's ear test to bleed easier with time due to the ear developing more capillaries due to the poking.