Just wanted to contribute a quick note for those who are still experiencing issues with changing the permissions via FTP.
If you are having trouble with PHP recognizing the mode as an integer, you can take the previous poster's method:
$mode = octdec ( str_pad ( $mode, 4, '0', STR_PAD_LEFT ) );
And add the following snippet right after:
$mode = (int) $mode;
This will force PHP to recognize the mode as an integer when you do:
ftp_chmod ( $conn_id, $mode, $path );
These together never seem to fail for me.