how can I access the dual brush?

I bought Harmony 12 Premium recently and one of the most important features I was looking forward to using was the Dual Brush, but can’t access it, the panel for dual brush and transparency is not appearing even after I click the big arrow in the brush properties panel, any help

to use the dual brush, click on the + icon on the timeline and select Drawing, select Lineart Bitmap or Color art Bitmap, but anyways if you go to the brush properties and click the big arrow icon you access the dual brush from there, there are many options so it would be best to read the brush Paint pdf for harmony here’s the link to download the pdf’s right from toon boom I have Harmony premium so whatever pdf’s work for the harmony you have they’re all there on the link