Transaction isolation

Hi,
I tried to find information about my problem but no clear solution so far.
What should I do to keep transactions isolated?

I have a script like one copied from post from February:

  >>> from pysqlite2 import dbapi2 as sqlite
  >>> con = C=sqlite.connect("/path")
  >>> C = con.cursor()
  >>> C.execute("begin")
  >>> C.execute("delete from t;")
  >>> C.executemany("insert into t values(?);", (1,2,3))
Traceback (most recent call last):
    File "<interactive input>", line 1, in <module>
OperationalError: SQL logic error or missing database
  >>>

When I give up "C.execute("begin")" everything is fine except for 
transaction isolation.
I have another concurrent connection (ODBC) and it reads empty set if I 
query table between DELETE and INSERT from previous connection.
What should I do?

Pawel Lewicki