iPad mini stylus

I found that after purchasing a hand stylus and ipadmini that there was no functionality with the two in an app like Penultimate.

I was determined to use the ipad mini for hand written notes.

So, I searched for a new app.

I was so happy to find that the stylus worked great in UPAD lite.

My question - How can the stylus works so good in one app, but fall so short in another?

Does it have to do with the app programming?