CASE1.DM.sql test fails

select cidx, CDATE from datatypetestm order by CASE CDATE WHEN '9999-12-27' THEN '2009-01-01' WHEN '9999-12-27' THEN '2009-01-01' ELSE NULL END, cidx;

ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near '<cache>('9999-12-27') then '2009-01-01' when <cache>('9999-12-27') then '2009-01' at line 1