check your folder access permissions on your FTP, or the the file address is not correct...
Try this to found the absolute link :
You can get this information through the PHP super-global variable "$_SERVER['DOCUMENT_ROOT']".
To know its value, you must create a file with the extension .php and containing the following code:
PHP:
<?php
echo $_SERVER["DOCUMENT_ROOT"]
?>
Place the file on your hosting (folder upload, in your case) and then indicate the address of the file in your internet browser (e.g.:
http://www.mysite.com/my_file.php
)