Why can't test function see my py.test fixtures?

I have the following structure:

demo/
  conftest.py
  test_1.py
  test_2.py

with conftest.py content being:

import pytest
@pytest.fixture()

def my_fixture():
print  "testing"*

and test_1.py content being:

def test_my_fixture(my_fixture):
    my_fixture

and test_2.py content being:

 import pytest

 @pytest.mark.usefixtures('my_fixture')
 def test_my_fixture():
     my_fixture

When executed tests with py.test -s, I get NameError for the fixture in test_2.py but not in test_1.py; why?

Here is the output:

================ test session starts ================
platform linux2 -- Python 2.7.3 -- py-1.4.26 -- pytest-2.6.4
plugins: timeout, random
collected 2 items 

test_1.py testing
.
test_2.py testing
F

===================== FAILURES ======================
__________________ test_my_fixture __________________

    def test_my_fixture():
>       my_fixture
E       NameError: global name 'my_fixture' is not defined

test_2.py:7: NameError