D'après le dernier message d'erreur
-soit le répertoire n'existe pas sur le serveur distant
-soit tu n'as pas donné les droits nécessaires en écriture dans ce répertoire.

Cela peut-être autre chose mais as-tu déjà vérifié ces deux point?

<?php
// include ur config file
include ("config.php");

// post all vars
if(isset($_POST['date'])) $date = $_POST['date'];
else $date = '';
if(isset($_POST['img'])) $img = $_POST['img'];
else $img = '';
if(isset($_POST['url'])) $url = $_POST['url'];
else $url = '';

// require vars
$Destination = "images/"; 				// uploads destinations
$Allow_Ext="(gif|jpg|jpeg|png|bmp)"; 	// Allow extensions
$MaxFileSize = 999999; 					// max size in MO
$WidthMax  = 100;        				// max width in px
$HeightMax = 100;        				// max height in px

$FileName = $_FILES['img']['name']; 	// originale file name
$FileSize = $_FILES['img']['size'];		// original file size
$TempName = $_FILES['img']['tmp_name']; // temporary name in the server

// if folder doesnt exist, create it
   function RecursiveMkdir($Destination)
   {
      if (!file_exists($Destination))
       {
               RecursiveMkdir(dirname($Destination));

           mkdir('images', 0777);
       }
   }
// to insert into DB
$url = $Destination.$FileName;


//ext verif 1
$temp=explode('.',$FileName);				
$extension=strtolower($temp[count($temp)-1]);

//if folder exists, ignore mkdir
   if (!file_exists("images"))
   {
           RecursiveMkdir("images");
   }

//verif filename is loaded or not
if(empty($FileName)){
echo $ErrorMessage15;
echo $ErrorReturn;
}
// verif size
elseif ($FileSize > $MaxFileSize){
echo $ErrorMessage7.'&nbsp;'.$MaxFileSize;
echo $ErrorReturn;
}

// ext verif 2
elseif (!eregi($Allow_Ext,$extension)){
echo $ErrorMessage8;
echo $ErrorReturn;
}

// verif file exists into directory or not
elseif (file_exists($Destination.$img)) {
echo $ErrorMessage9;
echo $ErrorReturn;
} 
// everythin' is cool so load
else {

    $move = move_uploaded_file($TempName, $url);
if ($move)
{
			
//connect + insert
$connection = mysql_connect("$dbhost", "$dblogin", "$dbpassword") or die ($ErrorConnection);
$db = mysql_select_db($db_name, $connection) or die(mysql_error());
$sql = "INSERT INTO $gallery_table VALUES ('','$jour/$mois/$year','$img','$url_img')";
$result = mysql_query($sql,$connection) or die ($ErrorInsert);
// success
echo $ErrorMessage3.'<br>';
	}
else
			{
			echo $ErrorMessage4;
				}
				}
	mysql_close();
		
		?>

    $move = move_uploaded_file($TempName, $Destination.$FileName);

$FileName = $_FILES['img']['name'];  // original name of the file on the client machine
$FileSize = $_FILES['img']['size'];  // size, in bytes, of the uploaded file. 
$TempName = $_FILES['img']['tmp_name']; //The temporary filename of the file in which the uploaded file was stored on the server. 

$MaxFileSize = 100000;
$Destination = 'images/';
$Max_Width = 500; //largeur
$Max_Height = 500; //longueur

A quoi correspond $avatar ? est ce un champ de type "file" de ton formulaire ?

as-tu bien défini l'enctype dans le formulaire ?

UPLOAD_ERR_PARTIAL
Valeur : 3. Le fichier n'a été que partiellement téléchargé.

<INPUT TYPE="hidden" name="MAX_FILE_SIZE" value="999999"> presque 1 MO.

$MaxFileSize = 999999;
elseif ($FileSize > $MaxFileSize){
echo $ErrorMessage7.' '.$MaxFileSize;
echo $ErrorReturn;
}

UPLOAD_ERR_PARTIAL
Valeur : 3. Le fichier n'a été que partiellement téléchargé.

if(empty($avatar)){
echo "Pas de fichier a uploader<br/>";
}

Array ( [img] => Array ( [name] => bassam.gif [type] => [tmp_name] => [error] => 3 [size] =>