Set title for the second y-axis in scatter chart with by()

[Binh Pham]

Dear Statalisters,

I plot the chart as below

twoway (scatter var1 rev, sort) (scatter var2 rev, sort yaxis(2) msymbol(square_hollow)), ///
ylabel(0(100)500) by(, note("")) by(, legend(off)) by(periods) ytitle("1st title", axis(1)) ytitle("2nd-title", axis(2))

But the y-title for the second axis does not appear. I tried many options in the dialog but it seems everything does not work.

Could someone show me what is wrong with my plotting code? Note: I use Stata 15.

Many thanks.

[Nick Cox]

Consider this

sysuse auto, clear
scatter turn trunk mpg, by(foreign, l1title(left) r1title(right))

[Binh Pham]

Perfecto! Thank a lot, Dr. Cox!