when I use transactions I got errors I won't get with sqlite3 cli

[alsadi@pc1 ~]$ python
Python 2.5.2 (r252:60911, Sep 30 2008, 15:41:38) 
[GCC 4.3.2 20080917 (Red Hat 4.3.2-4)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import sqlite3
>>> cn=sqlite3.connect(':memory:')
>>> c=cn.cursor()
>>> c.execute('BEGIN TRANSACTION')
<sqlite3.Cursor object at 0xb7efada0>
>>> c.execute('create temp table tmp_main (id integer, b text)')
<sqlite3.Cursor object at 0xb7efada0>
>>> c.execute('insert into tmp_main (id) values (10);')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
sqlite3.OperationalError: SQL logic error or missing database
>>> 


[alsadi@pc1 ~]$ sqlite3 ':memory:'
SQLite version 3.5.9
Enter ".help" for instructions
sqlite> BEGIN TRANSACTION;
sqlite> create temp table tmp_main (id integer, b text);
sqlite> insert into tmp_main (id) values (10);
sqlite> select * from tmp_main;
10|
sqlite> 

and if the transaction line removed I get no error

[alsadi@pc1 ~]$ python
Python 2.5.2 (r252:60911, Sep 30 2008, 15:41:38) 
[GCC 4.3.2 20080917 (Red Hat 4.3.2-4)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import sqlite3
>>> cn=sqlite3.connect(':memory:')
>>> c=cn.cursor()
>>> c.execute('create temp table tmp_main (id integer, b text)')
<sqlite3.Cursor object at 0xb7ff6da0>
>>> c.execute('insert into tmp_main (id) values (10);')
<sqlite3.Cursor object at 0xb7ff6da0>
>>>