Changed the vsftpd. conf configuration file, and failed to start the vsftpd service.

After changing the vsftpd. conf configuration file, the vsftpd service fails to start. For more information, see <Linux Enterprise Application> Linux server application information </G>. [Root @ localhost ~] #/Etc/init. d/vsftpd restart
Disable vsftpd: [OK]
Start vsftpd for vsftpd_bak: [OK]
Start vsftpd For vsftpd: [failed]
You can log on to the ECS instance before it is changed. Once it is changed, it fails to start,
The vsftpd. conf configuration is as follows:
# Example config file/etc/vsftpd. conf
#
# The default compiled in settings are fairly paranoid. This sample file
# Loosens things up a bit, to make the ftp daemon more usable.
# Please see vsftpd. conf.5 for all compiled in defaults.
#
# Read this: This example file is NOT an exhaustive list of vsftpd options.
# Please read the vsftpd. conf.5 manual page to get a full idea of vsftpd's
# Capabilities.
#
# Allow anonymous FTP? (Beware-allowed by default if you comment this out ).
Anonymous_enable = YES
#
# Uncomment this to allow local users to log in.
Local_enable = YES
#
# Uncomment this to enable any form of FTP write command.
Write_enable = YES
#
# Default umask for local users is 077. You may wish to change this to 022,
# If your users CT that (022 is used by most other ftpd's)
Local_umask = 022
#
# Uncomment this to allow the anonymous FTP user to upload files. This only
# Has an effect if the above global write enable is activated. Also, you will
# Obviously need to create a directory writable by the FTP user.
# Anon_upload_enable = YES
#
# Uncomment this if you want the anonymous FTP user to be able to create
# New directories.
# Anon_mkdir_write_enable = YES
#
# Activate directory messages-messages given to remote users when they
# Go into a certain directory.
Dirmessage_enable = YES
#
# The target log file can be vsftpd_log_file or xferlog_file.
# This depends on setting xferlog_std_format parameter
Xferlog_enable = YES
#
# Make sure PORT transfer connections originate from port 20 (ftp-data ).
Connect_from_port_20 = YES
#
# If you want, you can arrange for uploaded anonymous files to be owned
# A different user. Note! Using "root" for uploaded files is not
# Recommended!
# Chown_uploads = YES
# Chown_username = whoever
#
# The name of log file when xferlog_enable = YES and xferlog_std_format = YES
# WARNING-changing this filename affects/etc/logrotate. d/vsftpd. log
# Xferlog_file =/var/log/xferlog
#
# Switches between logging into vsftpd_log_file and xferlog_file files.
# NO writes to vsftpd_log_file, YES to xferlog_file
Xferlog_std_format = YES
#
# You may change the default value for timing out an idle session.
# Idle_session_timeout = 600
#
# You may change the default value for timing out a data connection.
# Data_connection_timeout = 120
#
# It is recommended that you define on your system a unique user which
# Ftp server can use as a totally isolated and unprivileged user.
# Nopriv_user = ft1_cure
#
# Enable this and the server will recognize asynchronous ABOR requests. Not
# Recommended for security (the code is non-trivial). Not enabling it,
# However, may confuse older FTP clients.
# Async_abor_enable = YES
#
# By default the server will pretend to allow ASCII mode but in fact ignore
# The request. Turn on the below options to have the server actually do ASCII
# Mangling on files when in ASCII mode.
# Beware that on some FTP servers, ASCII support allows a denial of service
# Attack (DoS) via the command "SIZE/big/file" in ASCII mode. vsftpd
# Predicted this attack and has always been safe, reporting the size of
# Raw file.
# ASCII mangling is a horrible feature of the protocol.
# Ascii_upload_enable = YES
# Ascii_download_enable = YES
#
# You may fully customise the login banner string:
# Ftpd_banner = Welcome to blah FTP service.
#
# You may specify a file of disallowed anonymous e-mail addresses. Apparently
# Useful for combatting certain DoS attacks.
# Deny_email_enable = YES
# (Default follows)
# Banned_email_file =/etc/vsftpd/banned_emails
#
# You may specify an explicit list of local users to chroot () to their home
# Directory. If chroot_local_user is YES, then this list becomes a list
# Users to NOT chroot ().
# Chroot_list_enable = YES
# (Default follows)
# Chroot_list_file =/etc/vsftpd/chroot_list
#
# You may activate the "-R" option to the builtin ls. This is disabled
# Default to avoid remote users being able to cause excessive I/O on large
# Sites. However, some broken FTP clients such as "ncftp" and "mirror" assume
# The presence of the "-R" option, so there is a strong case for enabling it.
# Ls_recurse_enable = YES
#
# When "listen" directive is enabled, vsftpd runs in standalone mode and
# Listens on IPv4 sockets. This directive cannot be used in conjunction
# With the listen_ipv6 directive.
Listen = YES
#
# This directive enables listening on IPv6 sockets. To listen on IPv4 and IPv6
# Sockets, you must run two copies of vsftpd whith two configuration files.
# Make sure, that one of the listen options is commented !!
# Listen_ipv6 = YES

Pam_service_name = vsftpd
Userlist_enable = YES
Tcp_wrappers = YES
Please help me