[jQuery] onchange input

[dziobacz]

I have:

<form method="post" action="/rejestracja">  <table>
  <input type="text" name="sf_guard_user[username]"
id="sf_guard_user_username" /></td>
  <input type="submit" name="register" value="Zarejestruj" />
</form>

<p id="information"></p>


I would like after each change in input 'sf_guard_user_username' write
something between <p id="information"> </p>.


What is wrong in my code below:

$(document).ready(function()
{
    $('#sf_guard_user_username').onchange(function()
        {
           $("#information").html("ddddd");
    });
});


??