Linux – GnuTLS error -53: Error in the push function, using vsftpd

I am in the process of setting up my home FTP with virtual users on a CentOS 6.0. I am using the following guide.

I was able to run the first script vsftpd_virtual_config_withTLS.sh successfully and configured it accordingly.

I then run the add user script vsftpd_virtualuser_add.sh successfully and configure a virtual user.

I then run the following commands to allow Iptables to allow connections over port 21

sudo iptables -I INPUT -p tcp --dport 21 -j ACCEPT
sudo iptables -I OUTPUT -p udp --dport 21 -j ACCEPT
sudo /sbin/service iptables save
sudo /sbin/service iptables restart

I then restart the vsftpd server. I then try to connect to my newly configured ftp server (Encryption: Require explicit FTP over TLS) with Filezilla 3.5.0 (which uses GnuTLS: 2.10.5) and I get the following error when connecting.

Error:  GnuTLS error -53: Error in the push function.

I have tried other ftp clients such as Fireftp and it still fails to list the directory listing. I have also ensured that vsftpd, gnutls, and filezilla are all the latest version. I am however very unfamiliar with TLS so any help with this situation would be greatly appreciated. Thanks!

EDIT: Posting my vsftpd.conf file as requested

anon_world_readable_only=NO
anonymous_enable=NO
chroot_local_user=YES
guest_enable=NO
guest_username=ftp
hide_ids=YES
listen=YES
listen_address=[redacted]
local_enable=YES
max_clients=100
max_per_ip=2
nopriv_user=ftp
pam_service_name=ftp
pasv_max_port=65535
pasv_min_port=64000
session_support=NO
use_localtime=YES
user_config_dir=/etc/vsftpd/users
userlist_enable=YES
userlist_file=/etc/vsftpd/denied_users
xferlog_enable=YES
anon_umask=027
local_umask=027
async_abor_enable=YES
connect_from_port_20=YES
dirlist_enable=NO
download_enable=NO
#
# TLS Configuration
#
ssl_enable=YES
allow_anon_ssl=NO
force_local_data_ssl=NO
force_local_logins_ssl=YES
ssl_tlsv1=YES
ssl_sslv2=NO
ssl_sslv3=NO
rsa_cert_file=/etc/pki/tls/certs/vsftpd.pem

EDIT: After having trying quanta suggestion I am getting at least a failed directory listing in Filezilla. Below is my output from Filezilla.

Status: Connecting to [redacted]...
Status: Connection established, waiting for welcome message...
Response:   220 (vsFTPd 2.2.2)
Command:    AUTH TLS
Response:   234 Proceed with negotiation.
Status: Initializing TLS...
Status: Verifying certificate...
Command:    USER [redacted]
Status: TLS/SSL connection established.
Response:   331 Please specify the password.
Command:    PASS *********
Response:   230 Login successful.
Command:    SYST
Response:   215 UNIX Type: L8
Command:    FEAT
Response:   211-Features:
Response:    AUTH SSL
Response:    AUTH TLS
Response:    EPRT
Response:    EPSV
Response:    MDTM
Response:    PASV
Response:    PBSZ
Response:    PROT
Response:    REST STREAM
Response:    SIZE
Response:    TVFS
Response:    UTF8
Response:   211 End
Command:    OPTS UTF8 ON
Response:   200 Always in UTF8 mode.
Command:    PBSZ 0
Response:   200 PBSZ set to 0.
Command:    PROT P
Response:   200 PROT now Private.
Status: Connected
Status: Retrieving directory listing...
Command:    PWD
Response:   257 "/"
Command:    TYPE I
Response:   200 Switching to Binary mode.
Command:    PASV
Response:   227 Entering Passive Mode (192,168,1,10,251,213).
Command:    LIST
Error:  GnuTLS error -53: Error in the push function.
Error:  Connection timed out
Error:  Failed to retrieve directory listing

EDIT: Error seems to be with iptables. My iptables config is listed below.

# Generated by iptables-save v1.4.7 on Wed Aug 24 00:29:05 2011
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [157:20225]
-A INPUT -p tcp -m tcp --dport 21 -j ACCEPT
-A INPUT -p tcp -m tcp --dport 21 -j ACCEPT
-A INPUT -p tcp -m tcp --dport 60021 -j ACCEPT
-A INPUT -p tcp -m tcp --dport 2011 -j ACCEPT
-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
-A INPUT -p icmp -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -j REJECT --reject-with icmp-host-prohibited
-A INPUT -p tcp -m tcp --dport 2011 -j ACCEPT
-A INPUT -p tcp -m tcp --sport 1024:65535 --dport 64000:65535 -m state --state ESTABLISHED -j ACCEPT
-A FORWARD -j REJECT --reject-with icmp-host-prohibited
-A OUTPUT -p tcp -m tcp --sport 20 -j ACCEPT
-A OUTPUT -p udp -m udp --dport 21 -j ACCEPT
-A OUTPUT -p udp -m udp --sport 21 -j ACCEPT
-A OUTPUT -p udp -m udp --sport 60021 -j ACCEPT
-A OUTPUT -p tcp -m tcp --sport 2011 -j ACCEPT
-A OUTPUT -p tcp -m tcp --sport 2011 -j ACCEPT
-A OUTPUT -p tcp -m tcp --sport 20 -j ACCEPT
-A OUTPUT -p tcp -m tcp --sport 64000:65535 --dport 1024:65535 -m state --state RELATED,ESTABLISHED -j ACCEPT
COMMIT
# Completed on Wed Aug 24 00:29:05 201

Edit: When run the query that quanta suggested below I get the following

grep: /usr/src/kernels/2.6.32-71.29.1.el6.x86_64-x86_64/.config: No such file or directory

So ip_conntrack_ftp seems not to be loading correctly and I am not sure how to rectify this.