Warning: sqlsrv_query() expects parameter 1 to be resource, bool

<?php
//Connexion à la base de données
try {

$serverName = ".";

 $connectionOptions = array("Database"=>"mydatabase", "Uid"=>"sa", "PWD"=>"mypassword");

 $conn = sqlsrv_connect($serverName, $connectionOptions);

 echo"Connexion etablie";

}

catch (PDOException $error) {

die("Echec de connexion : " . $error->getMessage() );

}

// Affichage des colonnes de la table GI_Intervention dans un tableau

$sql = "SELECT NIntervention, Reference, DateIntervention, CClient, Adresse, Cloture FROM GI_Intervention";

$stmt = sqlsrv_query($conn, $sql );
//var_dump($stmt);
while( $row = sqlsrv_fetch_array( $stmt, SQLSRV_FETCH_NUMERIC) ) 
{
?>
	<tbody>
    	<tr>
        	<td><input type="checkbox" name="" /></td>
            <td><?php echo $row[0]."<br>"; ?></td>
			<td><?php echo date_format($row[2], 'Y-m-d')."<br>";?></td>
			<td> <?php echo $row[3]; ?> </td>
            <td><?php echo $row[4]."<br>"; ?></td>
            <td><?php echo $row[5]."<br> <br>"; ?></td>
         
        </tr>
		
	<?php
	}
    sqlsrv_free_stmt( $stmt);
	
    
?>