Paint area problem

I am quite new to skatter and thus tried to follow the Get Started tutorial. The problem that arose was that I cannot make the Paint Area feature to work, no matter how big or small the brush is set.

Any ideas, please?

Edson

Is “Use Surface boundaries as include area” checked? Is the Paint Area set as Include or Exclude?

I was probably forgetting to click on something like this. it is working now. thanks.