its possibly throwing you because you're not used to having to push the mouse around as much as you do with a pen..
I think that's exactly the problem I'm having now you mention it. I only move the mouse a tiny amount to go from corner to corner, yet the pen obv has to be moved across the span of the tablet, good point.
I'm sure I'll get the hang of it soon enough, I used it again today and found it much better than my first try, but still awkward to match pen with position. I just like to learn things quickly, prob too quickly!
it could also be that you need a larger tablet so you can draw more from your elbow than your wrist?
If you mean for a pain viewpoint, it's only the mouse that gives me a sore wrist, the pen is fine in that regard, which is why I bought it. I just need to get the hang of it now! My 8 year old loves it straight up, he's making all sorts of computer drawings he could never do before.
How many out there use a tablet for PPing over a mouse?