Select policy,exp_mod,max(eff_date) from table exp_mod_table ;
group by policy,exp_mod into cursor xxx


Try this:

SELECT policy, max( eff_date ) as eff_date FROM table exp_mod_table GROUP BY policy INTO CURSOR xxx

SELECT e.policy, e.exp_mod, e.eff_date FROM exp_mod_table e INNER JOIN xxx ON xxx.policy = e.policy and xxx.effdate = e.eff_date INTO CURSOR yyy