Warning: Illegal string offset 'name' in

$action 	= 'new';
$a 			= !empty($_GET['a']) ? $_GET['a'] : NULL;
$submit 	= !empty($_POST['submit']) ? $_POST['submit'] : NULL;
$haction 	= !empty($_POST['haction']) ? $_POST['haction'] : NULL;

$idart 		= !empty($_REQUEST['idart']) ? $_REQUEST['idart'] : NULL;
$article 	= !empty($_POST['article']) ? $_POST['article']['name'] : '';
$lieuart 	= !empty($_POST['lieuart']) ? addslashes($_POST['lieuart']) : '';
$dateart 	= !empty($_POST['dateart']) ? dw2m($_POST['dateart']) : '';
$descart 	= !empty($_POST['descart']) ? $_POST['descart'] : '';

switch($a) {
	case 'new': $action = 'new';  break; 
	case 'ls' : $action = 'list'; break;
	default   : $action = 'new';  break; 
}

if($submit) {

	switch($haction) {
		case 'new':
			$extensions_valides = array( 'pdf' );
			//1. strrchr renvoie l'extension avec le point (« . »).
			//2. substr(chaine,1) ignore le premier caractère de chaine.
			//3. strtolower met l'extension en minuscules.
			$extension_upload = strtolower(  substr(  strrchr($_FILES['article']['name'], '.')  ,1)  );
			if (!in_array($extension_upload,$extensions_valides) ) {
				$erreur = "<span class='erreur'>Vous devez ajouter un fichier de type PDF</span>";
			} else {
				
			$sql = "INSERT INTO cdc_articles (article, lieuart, dateart, descart) VALUES (:article, :lieuart, :dateart, :descart)";
			$datas = array('article' => $article, 'lieuart' => $lieuart, 'dateart' => $dateart, 'descart' => $descart);
			$result = executeQuery($sql,$datas);
			$typenr = "enregistré";
			$reqaj = $requete; 
			$success = "<span class='success'>Le nouvelle article du - ".dFR("$dateart")." - a été $typenr.</span>";
			}
			break;
	}
}

switch($action) {
	case 'new':   
		$title      = "Saisie d'un Article";
		$btsub      = "Enregistrer";
		$idart     	= "";
		$article   	= "";
		$lieuart   	= "";
		$dateart  	= "";
		$descart  	= "";
		break;

	case 'list': 
		$title  	= "Liste des Articles";
		break;
}