Не пойму почему не работает move_uploaded_file()

<?php
 
$uploaddir = 'image/';
$uploadfile = $uploaddir . basename($_FILES['image000']['name']);
 
 
if (move_uploaded_file($_FILES['image000']['tmp_name'], $uploadfile)) {
    echo "\nOk.\n";
} else {
    echo "\nError!\n";
}
print_r($_FILES);
?>

$uploaddir = '/home/localhost/www/image';
if(!is_dir($uploaddir)){
    mkdir($uploaddir);
    $uploadfile = $uploaddir . basename($_FILES['image000']['name']);
      if (move_uploaded_file($_FILES['image000']['tmp_name'], $uploadfile)) {
         echo "\nOk.\n";
      } else {
            echo "\nError!\n";
      }
print_r($_FILES);
}

if ($dir = opendir('img/')) {
        $for_open1=".bmp";
        $for_open2=".jpg";
.....
}

<?php
$uploaddir = '/home/172.16.250.4/www/image';
$uploadfile = '';
 
if(is_uploaded_file($_FILES['image000']['tmp_name'])){
    echo "\nDownloaded.\n";
} else {
    echo "\nError of download!\n";
}
 
if(!is_dir($uploaddir)){
    mkdir($uploaddir);
}
$uploadfile = $uploaddir . basename($_FILES['image000']['name']);
if (move_uploaded_file($_FILES['image000']['tmp_name'], $uploadfile)) {
    echo "\nOk.\n";
}else{
    echo "\nError!\n";
}
 
print_r($_FILES);
print_r($uploadfile);
?>

$uploaddir = '/home/172.16.250.4/www/image';