JQuery AJAX-PHP mkdir() issue

I've been trying to get a script to work that calls a PHP file into a jQuery script using AJAX.

var dataString = 'Submit=Set';
$.ajax({
   type: "POST",
   url: "./inc/php/file.php",
   dataType: "json",
   data: dataString,
   success: function(data) {
    $('.error').html(data.errormsg+' OK.');
   },
   error: function(data) {
    $('.error').html(data.errormsg+' OH NO.');
    }
});

and it's calling this bit of PHP

$blogstatus =array();
$blogstatus['errormsg'] = 'NOTHING';
if(isset($_POST['Submit'])){ 
$blogstatus['errormsg'] = 'FIRST';

if (file_exists('/files/subfolder/')){
    $blogstatus['errormsg'] = 'exists';
}else{
    $blogstatus['errormsg'] = 'YES';
    mkdir('.开发者_运维百科/files/subfolder/',0777);
}
echo json_encode($blogstatus);  

If i take the mkdir out everything runs fine and i can call errormsg. I've tried running the mkdir without the ajax call in a standard PHP script, and that worked. Everytime i put the mkdir into the script i get the errormsg variable as undefined and the script fails.

Im fairly new to using jquery so it maybe something simple im over looking. cheers for any heelp

---

Please make sure the following points are satisfied:

Make sure the parent folder has the permission for apache to run your command?

Also, remove the trailing slash from your command

mkdir('./files/subfolder/',0777);

to

mkdir('./files/subfolder',0777);
- it is good to supply the full path when it comes to linux commands. For ex:

mkdir('/var/www/html/someproject/somemodule/files/subfolder',0777);