Hi again ,
Finally , it was the definition of the path on my layout file :
<?php echo $this->headLink()->appendStylesheet('http://zendtest.local/media/css/style.css'); ?>
Using an absolute path solved my problem ,it works .
But now ,when observing the source code of my browser when loading the page I mention that the "style link" is mentioned twice ;
<link href="style.css" media="screen" rel="stylesheet" type="text/css" />
<link href="http://zendtest.local/media/css/style.css" media="screen" rel="stylesheet" type="text/css" />
I can't explain that , although my application works on my local development environment ;
< ?php
/* Comments : Thanks to this forum */
JohnD