程序如下，运行结果LEGEND还是在BOTTOM CENTER OUTSIDE. 代码完全没有问题吧？

PROC SGPLOT DATA = n_final DESCRIPTION = &name;
    ODS GRAPHICS ON / RESET = INDEX IMAGEFMT = PNG IMAGENAME = &name;
    TITLE ;
    WHERE flag = 'A';
    LEGEND POSITION = (TOP CENTER OUTSIDE) MODE = PROTECT;
    XAXIS LABEL = &xLabel TYPE = DISCRETE;
    YAXIS LABEL = &yLabel;
    SERIES X = yyyymm Y = N / MARKERS LEGENDLABEL = &yLabel GROUP = range;
RUN;