I am using Stata 13
I want to develop code to add a single vertical line on a graph using a value obtained from a dataset rather than having to hard code the position of the line. This would make the code general.
I thought I would do it by saving a value from the data set in a macro variable and use the macro variable to substitute into the xline graph option.
The code below fails to add a line when I use the macro variable.

Is there something else I should be doing to get this to work?

set obs 12
gen y = 42
gen time = _n/y*100
line y time, xline(7)

global time1 7
macro list

line y time, xline(`time1')