'Error Message' "language plpgsql does not exist

[John Foster <jfoster@augustmail.com>]

I got this error when setting up SQL-Ledger>

Error!


CREATE FUNCTION del_yearend() RETURNS OPAQUE AS '
begin
 delete from yearend where trans_id = old.id;
 return NULL;
end;
' language 'plpgsql';

ERROR: language "plpgsql" does not exist

Any ideas as to what or why?


-- 
John Foster