data flow;
  /*put x= y= z= _n_;*/
  input x y;
  z=x+y;
  put x= y= z=;
  put _n_= _error_=;
  cards;
10 20
100 200
1000 2000
;
run;
proc print;
run;
运行时，结果窗口没显示，日志窗口显示错误：Module sasztx   not found in search paths，这是怎么回事？请各位大神指点