Hello.
i have problem when running risk set sampling macro.
i  found this macro on this(http://mchp-appserv.cpe.umanitoba.ca/Upload/SAS/risk_set_sampling_macro.sas.txt)
 
this is my marco typing on SAS
%risk_set_match (cohort_name = CASE_CTRL,
                       outcome_var = outcome,
                       end_fu = END_EPI,
                       randnum = 123,
                       K = 20,
         control_index_dt = case_fu,
         rs_match_where = a.sex=b.sex
         id = JID,
         time0 = START_EPI,
         gender = sex,
         agevar = age,
         output_name = matched1,
         no_match = N
                      );
 
In the middle of macro, there is
-----------------------------------------------------------
   proc sql;
      create table risk as
      select
    a.&id. as case_ID,
             b.&id. as control_ID,
    a.&agevar. as case_age,
          b.&agevar. as control_age,
             a.&gender. as case_sex,
             b.&gender. as control_s,
             a.&time0. as case_t0,
             b.&time0. as control_t0,
          a.&end_fu. as case_endfu,
             b.&end_fu. as control_endfu,
          a.caco as case_caco,
          b.caco as control_caco,
             a.index_date,
             a.match_num
      from case_caco1_I a,
           controls b
      where &rs_match_where;
   quit;
   proc append base = risk_set data = risk;
   run;
----------------------------------------------------------------
In here such as case_ID, from ~~~, i have got errors.
ERROR 22-322 ~~~~
 
please answer me TT