I wonder if anyone might kindly assist with an issue I have encountered in the labeling of groups in sts graph.

I wish to display a Kaplan-Meier failure plot with a line by each of two groups. (stored in variable curvelabel as Group 1 and Group 2).

The plotting is accurate, however the legend and number-at-risk display the groups as "curvelabel=Group 1", rather than simply "Group 1". Even with instruction to the legend command, I cannot alter this legend labelling (although the command correctly overwrites the 95% CI labels)

I attach a picture which shows the issue and, beneath that, the code leading to the issue.

Any advice warmly welcomed!

Array

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Here, the time to event data is stored as doublette and doubleevent.

Code:
label define curvelabel_ 1 "Group 1" 2 "Group 2"
label values curvelabel curvelabel_
label variable curvelabel "Groupings for Failure Plot"

stset doublette, f(doubleevent)
sts graph, ci failure ///
    risktable(, size(small)) ///
    tmax(3660) ///
    ci1opts(color(blue%10)) ///
    ci2opts(color(red%10)) ///
    ytitle(Proportion Experiencing Failure) ///
    ylabel(0 "0" 0.25 "25" 0.5 "50" 0.75 "75" 1 "100") ///
    xtitle(Days Follow-up) xlabel(#8) ///
    title(Failures)    ///
    by(curvelabel) ///
    legend (label(1 "Group 1 95% CI") label(2 "Group 1") label(3 "Group 2 95% CI") label(4 "Group 2"))