Why does the s pen not work in some areas of the screen?

C

Christi

When i'm using the s pen, particularly in the note function, it does not work in the centre right hand section of the screen. Using my finger does work in this area though. Any ideas anyone? The phone is less than 2 years old, is with O2 & insured with them but I'm unsure about claiming due to the excess. I did drop it & there is a small ding in the top right corner of the metal rim so concerned they may say this caused it (I don't think it did) & not cover it under warranty. Can anyone advise?