求教大神，这样代码错在什么地方？运行总是报错，var1 avr2 var3没有被引用之类的。求教，谢谢！
/* Adding Prefix on Selected Variables */
%macro addprefix(lib,dsn,start,end,newname);
proc sql noprint;
select nvar into :num_vars
from dictionary.tables
where libname="&LIB" and memname="&DSN";
select distinct(name) into :var1-:var%trim(%left(&num_vars))
from dictionary.columns
where libname="&LIB" and memname="&DSN";
quit;
run;
proc datasets library = &LIB;
modify &DSN;
rename
%do i = &start. %to &end.;
&&var&i = &newname_&&var&i.
%end;
;
quit;
run;
%mend addprefix;
截图如下：