请教各位大佬为什么会报错呢？谢谢！
sas document上的一个例子 直接复制粘贴 到sas studio 运行后报错，最后只得到7条obs，实际上应该有395条obs

data ShoesByRegion;   set sashelp.shoes;    by descending Region       descending Subsidiary;run;

ERROR: BY variables are not properly sorted on data set SASHELP.SHOES.
Region=Africa Product=Women's Dress Subsidiary=Addis Ababa Stores=12 Sales=$108,942 Inventory=$311,017 Returns=$3,233 FIRST.Region=0
LAST.Region=0 FIRST.Subsidiary=0 LAST.Subsidiary=0 _ERROR_=1 _N_=8
NOTE: The SAS System stopped processing this step because of errors.
NOTE: There were 9 observations read from the data set SASHELP.SHOES.
WARNING: The data set WORK.SHOESBYREGION may be incomplete.  When this step was stopped there were 7 observations and 7 variables.