file handle在帮助文件里面解释的挺清楚，我做下面这几步，却总是提示我file handle没有打开，
closeall;
let varname = id name age year exp;
create fout = out1 with ^varname,5,4;

xx=rndn(10,5);
show;
writer(fout,xx);
close(fout);



error G0127 : File not open for write


为什么？