SQL & PL/SQL

Hello,
Here are the steps I followed,
a) create type idList is table of number;
b) CREATE OR REPLACE procedure exp_type (my_list out IdList)
is
i number := 1;
cursor c is
select val from exp_array;
begin
for rec in c
loop
i := i + 1;
my_list(i) := rec.val;
end loop;
end;

c) DECLARE
MY_LIST1 IdList;
BEGIN
EXP_TYPE ( MY_LIST1);
dbms_output.put_line('COUNT IS '||my_list1.count);
END;

Here I get ORA-06531: Reference to uninitialized collection error on the procedure.

Could you please let me know how to avoid this error ?

thank you,
Madhu