The first inch of almost any blade is the most used. Therefore it's generally the dullest part of the blade. Which means it needs more work than the rest. On many blades this means you need to spend a LOT of extra time on that first inch. Including the tip. This is a generalization, but it's more true than not.
If the whole blade is sharp, but it's just the point that's dull, it's time to look at it. Really look at it close. If you have a loupe or magnifying glass, use it. You will probably be surprised by what you see, but seeing the actual *shape* of the dull tip is going to show you what to do. You're probably going to find that the point is bulbous and rounded. To make it pointy again, you have to grind away metal until the point forms two lines or arcs that meet at the *very* tip at a nice sharp intersection.
Depending upon how dull the tip is, this might require a good amount of work. Or only a little. If it needs a lot, you're better off focusing on that area with a real bench stone, and then finishing up with the sharpmaker. If it only needs a little work, then use the sharpmaker. As the guys above have said, don't let the tip come off of the stone. That "skating off" action is one of the ways the tip gets rounded off in the first place! So, as Italian said, sharpen *right up* to the tip, but not past it.
You'll know you've done a good job when the tip of the blade catches your finger prints and digs in, much like a push pin would if you lightly drag your finger across the sharp point. Try this before, during, and after so you can have a gauge of your progress.
Extra time
Loupe (Observation)
Remove roundness to form sharp intersection
Patience
Brian.
