Login div doesn't work with jquery fancybox

Login div doesn't work with jquery fancybox

i have a bug with my jquery fancybox but i don't know where the bug is. If
i click on the a href tag, the pop up window doesn't work... :(
Here my Testsite: http://topkosmetikstudios.de/release/index.php?article_id=1
The Logiin Button (Anmelden) is at the top on the right side.
Here my Code:
<a href="#login_form" class="user show_login_form">
Anmelden
</a>
<!-- ToDo mit-->
<div class="login_form_modal_container">
<div id="login_form" class="box">
<h3>User login</h3>
<div class="box-content clearfix">
<form action="#">
<input type="text" placeholder="Enter your
email" name="email">
<input type="password" placeholder="Enter
your password" name="pass">
<label for="remember"
class="custom_checkbox remember_me"><input
type="checkbox" name="remember"
id="remember">Remember me</label>
<a class="button submit red right">Login</a>
<a href="#" class="forgotten_pass
right">Forgot your password?</a>
</form>
</div>
</div>
</div>
I hope anybody can help my to find my bug or problem.
Regards,
Dave