Php 图像上传脚本

我正在尝试使以下脚本正常工作，但不断出现以下错误：

警告：getimagesize（）：第17行/var/sites/r/domain.co.uk/public_html/dev/test.php中的文件名不能为空 上传文件。

第17行是：

list（$width，$height）=getimagesize（$\u FILES['fileup']['tmp\u name']）

tmp\u name
来自哪里？我不确定。我不是PHP专家。此代码已运行，然后突然停止。我已经和主机公司打了一个电话，看看那里是否有任何变化。（同时，你可以试着找出
$\u文件['fileup']
（和
$\u文件['file']
），我已经把这一点缩小到主机的问题上，因为同样的脚本在其他主机上工作得很好。）。
<?php
   error_reporting(E_ALL);

   if (isset($_POST['update_photo'])) {

   $uploadpath = '../operator_images/';      // directory to store the uploaded files
   $max_size = 2000;          // maximum file size, in KiloBytes
   $alwidth = 200;            // maximum allowed width, in pixels
   $alheight = 200;           // maximum allowed height, in pixels
   $allowtype = array('bmp', 'gif', 'jpg', 'jpe', 'png');        // allowed extensions

   if(isset($_FILES['fileup']) && strlen($_FILES['fileup']['name']) > 1) {
     $uploadpath = $uploadpath . date('Ymdhis') . basename( $_FILES['fileup']['name']);       // gets the file name
     $sepext = explode('.', strtolower($_FILES['fileup']['name']));
     $type = end($sepext);       // gets extension
     list($width, $height) = getimagesize($_FILES['fileup']['tmp_name']);     // gets image width and height
     $err = '';         // to store the errors

     // Checks if the file has allowed type, size, width and height (for images)
     if(!in_array($type, $allowtype)) $err .= '<span style="color: #FFFFFF; ">The file: <b>'. $_FILES['fileup']['name']. '</b> not has the allowed extension type.</span>';
     if($_FILES['fileup']['size'] > $max_size*1000) $err .= '<span style="color: #FFFFFF; "><br/>Maximum file size must be: '. $max_size. ' KB.</span>';
     if(isset($width) && isset($height) && ($width >= $alwidth || $height >= $alheight)) $err .= '<span style="color: #FFFFFF; "><br/>The maximum Width x Height must be: '. $alwidth. ' x '. $alheight .'</span>';

     // If no errors, upload the image, else, output the errors
     if($err == '') {
       if(move_uploaded_file($_FILES['fileup']['tmp_name'], $uploadpath)) { 
         echo '';
         if(isset($width) && isset($height)) echo '';
         echo '';
       }
       else echo '<b>Unable to upload the file.</b>';
     }
     else echo $err;
   }

   }

   echo "<form action='test.php' method='post' enctype='multipart/form-data' data-abide>

    <div class='input-wrapper'>
    <label style='color: #000000; ' for='filebutton'>Select File</label>
    <input id='file' name='fileup' type='file'>
    </label>
    </div>

     <div><button type='submit' class='button expand radius success' name='update_photo'>Upload Photo</button></div>

    </form>";

   ?>