I have an FTP user whose default is /root/ftpuser

This user can login fine. The user is the owner of the directory & the directory is even set to 777 permissions.

But the user can't upload anything, the display is:

Status: Connecting to xx.xxx.xxx.xx:21...
Status: Connection established, waiting for welcome message...
Response:   220---------- Welcome to Pure-FTPd [privsep] [TLS] ----------
Response:   220-You are user number 2 of 50 allowed.
Response:   220-Local time is now 05:12. Server port: 21.
Response:   220-This is a private system - No anonymous login
Response:   220-IPv6 connections are also welcome on this server.
Response:   220 You will be disconnected after 15 minutes of inactivity.
Command:    USER ftpuser
Response:   331 User ftpuser OK. Password required
Command:    PASS *********
Response:   230 OK. Current restricted directory is /
Command:    OPTS UTF8 ON
Response:   200 OK, UTF-8 enabled
Status: Connected
Status: Starting upload of test.html
Command:    CWD /
Response:   550 Can't change directory to /: Permission denied
Command:    MKD /
Response:   550 Can't create directory: Permission denied
Command:    CWD /
Response:   550 Can't change directory to /: Permission denied
Command:    SIZE /btn.png
Response:   550 Can't check for file existence
Command:    TYPE I
Response:   200 TYPE is now 8-bit binary
Command:    PASV
Response:   227 Entering Passive Mode (66,232,106,33,52,218)
Command:    STOR /test.html
Response:   553 Can't open that file: Permission denied
Error:  Critical file transfer error

It's a Linux CentOS 6 server.

Any ideas?