用于上传大型文件的空FILES数组

我有一些遗留代码，对于我的生活，我不明白为什么它突然停止工作。

非常基本的上传脚本:

if($_FILES['csvfile']['name']){
    //if no errors...
    if(!$_FILES['csvfile']['error']){
        //now is the time to modify the future fle name and validate the file
        $new_file_name = strtolower($_FILES['csvfile']['tmp_name']); //rename file

       //move it to where we want it to be
       move_uploaded_file($_FILES['csvfile']['tmp_name'], 'active_leads1.csv');
       //echo 'Congratulations!  Your file was accepted.';
    }else{
      //set that to be the returned message
      //echo 'Ooops!  Your upload triggered the following error:  '.$_FILES['csvfile']['error'];
       die("Unfortuanatly there was an error: {$_FILES['csvfile']['error']}");
   }
}else{
    die("Unfortuanatly there was an error: ".print_r($_FILES,true)."");
}

同样的形式也是基本的:

<form action="csvconvert.php" method="post" enctype="multipart/form-data">
 <input type="file" name="csvfile" size="25" />
 <input type="submit" name="submit" value="Submit" />
</form>

但是，它在11MB的文件上失败了。

检查了post限制和上传限制，两者都很好(256M和128M)，最大输入时间是240，但是如果我print_r $_POST和$_FILES它们都是空的。

以前有人遇到过这个吗?任何帮助将不胜感激!