Unrecognized variable

Hello,
I try to use a variable "$ user = $ this-> html ('html.user', $ target);" (The answer is "eric"
This variable displays the username of the member concerned.
But when I want to use this variable in a php, it is not seen.
So to test, I wrote the hard varaible: "$ user =" eric ";" And there my php works.

Do you know why ?

Best regards.
Eric

<?php
// Username de l'ami
$utilisateur = $this->html('html.user', $target); //(Returns "eric"
//$utilisateur = "eric"; // pour test

//ID de l'ami
$db = JFactory::getDBO();
$query = $db->getQuery(true);
$query->select($db->quoteName('id'));
$query->from($db->quoteName('#__users'));
$query->where($db->quoteName('username') . ' = '. $db->quote($utilisateur));
/$db->setQuery($query);
$results = $db->loadResult();

// echo $results;
?>