I have iPad Air-1

Latest version of the Artrage for iPad.

My stylus: Wacom Thinline -1 (not the current latest one - the earlier model)

I have updated the stylus firmware through Wacom Stylus Update

I have iOS 8.xx - whatever was the last iOS 8.

I will never update it to iOS 9 for reasons of my own.

My issue:

The Chalk tool does not allow line thickness variation at different pressure levels - but it shows density varioations - lighter & darker. But the size of the chalk remains the same - does not get thinner & wider.

Is this feature not available with ArtRage for iPad or is something wrong with My settings? The feature works with oil paint.

Thanks in advance