Oracle Database Discussions

Hi,
is AUTOCOMMIT=FALSE, workd differently on Insert and Delete ? I'm on 10gXE and SQL Developer
I can't understand why I have situation like below:

Tx
T

create table  tt (c1 int,  c2 char2(200));
alter session set AUTOCOMMIT=FALSE;
insert   into  tt values (s1.nextval, 'XXXXXXXXXX');
insert   into  tt values (s1.nextval, 'XXXXXXXXXX');
insert   into  tt values (s1.nextval, 'XXXXXXXXXX');
select COUNT(*) from tt;  = 0
commit;       -------- AUTOCOMMIT STILL FALSE
select COUNT(*) from tt;  = 3
delete from tt; 
-- 3 Row(s) affected  
select COUNT(*) from tt;  = 0  --------- why ? ????  expect it =3, AUTOCOMMIT still set =FALSE