553 Could not create file(vsftpd upload)

whoinmyheart

anonymous_enable=YES
local_enable=YES
write_enable=YES
local_umask=022
anon_upload_enable=YES
anon_mkdir_write_enable=YES
dirmessage_enable=YES
xferlog_enable=YES
connect_from_port_20=YES
chown_uploads=YES
chown_username=root
xferlog_file=/var/log/vsftpd.log
pam_service_name=vsftpd
userlist_enable=YES
#enable for standalone mode
listen=YES
tcp_wrappers=YES
-------------------------------------------------------------
the text above is my file /etc/vsftpd/vsftpd.conf
-------------------------------------------------------
my vsftp version is vsftpd-1.2.0-4
-----------------------------------------------------
when login the server as "anonymous", login!
but when i want to upload a file .for example "1.mp3"
the ftp will tell me this information below
-------------------------------------------------------
正在查阅 172.24.21.121
尝试 172.24.21.121：21
已连接到 172.24.21.121:21
220 (vsFTPd 1.2.0)
USER anonymous
331 Please specify the password.
PASS xxxx
230 Login successful.
SYST
215 UNIX Type: L8
TYPE I
200 Switching to Binary mode.
PWD
257 "/"
PASV
227 Entering Passive Mode (172,24,21,121,67,175)
LIST -aL
150 Here comes the directory listing.
226 Directory send OK.
CWD /pub
250 Directory successfully changed.
PWD
257 "/pub"
PASV
227 Entering Passive Mode (172,24,21,121,204,93)
LIST -aL
150 Here comes the directory listing.
226 Directory send OK.
正在从缓存中装入目录列表 /pub
PASV
227 Entering Passive Mode (172,24,21,121,183,10)
STOR /pub/16163.html
553 Could not create file.
PASV
227 Entering Passive Mode (172,24,21,121,54,5
LIST -aL
150 Here comes the directory listing.
226 Directory send OK.
---------------------------------------------------------
that is all !! who can tell me the reason!!!