jquery.click function problem

jquery.click function problem

Hello,

I'm trying to do the following: when a user clicks on a checkbox an alert message box must appear.

I have try with the following code but does not work:

<h3>Listado</h3>
<p></p>
<table border="1">
 <thead>
 <tr>
 <th>Sel</th>
 <th>Apellidos</th>
 <th>Nombre</th>
 <th>Seccion</th>
 </tr>
 </thead>
 <tbody>
 
 <tr>
 <td><input id="check1" type="checkbox" value="1" /></td>
 <td>Martin Martin</td>
 <td>Enrique</td>
 <td>embalajes</td>
 </tr>
 
 </tbody>
</table>
<script>
jQuery('#check1').click(function() {
 alert('Hola');
 });
</script>

As I could read on the jquery api examples, this code is very close to the 
examples that are published there but I do not understand why this one does not work.
Anyone could help me, please??

Thanks in advance