Hello everybody!
I wanted to plot volume.
Tried this code:
vars Vol = series(marketVol());
plot("Volume", Vol, NEW | BARS, BLUE);
Got 0 on the graph.
What did I do wrong?

Do I need Zorro S to use marketVol() function?

Yes, and the manual confirms it:
https://zorro-project.com/manual/en/price.htm

Thank you.