If I hadn't figured out the solution to this problem then this would probably be a cry for help, but instead I hope this will be a bit helpful.
I think I'll run down a couple of solutions I've found and stuff. Bear in mind that even though I've found several solutions they won't necessarily work for you and these aren't ALL the solutions either, and if the problem persists perhaps you should seek professional help, as I am only an internet lurker who has depended on Google and other sources. And please, I'm not a tech whiz, so if you continue to have issues, I'm not necessarily the one you should come running to for help. I can try, but Google and professional help are probably better than I am.
I'll talk a little first.
I've run into many problems in SAI with the pen sensitivity. What is pen sensitivty? Well basically,
It allows you to vary the width of your pen strokes with how much pressure you apply to it, and almost