openvpn bug auth pam mysql

client.ovpn :
client
port 1194
proto tcp
dev tun
remote abc.abc.com
resolv-retry infinite
ca ca.crt
tls-auth ta.key 1
cipher AES-256-CBC
comp-lzo
verb 3
nobind
persist-key
persist-tun
mute-replay-warnings
auth-user-pass
ns-cert-type server
mute 20

server.conf :
port 1194
proto tcp
dev tun
ca /etc/openvpn/keys/ca.crt
cert /etc/openvpn/keys/server.crt
key /etc/openvpn/keys/server.key
dh /etc/openvpn/keys/dh2048.pem
tls-auth /etc/openvpn/keys/ta.key 0
cipher AES-256-CBC
server 10.8.0.0 255.255.255.0
#push route 192.168.0.0 255.255.255.0
#push redirect-gateway def1
ifconfig-pool-persist ipp.txt
duplicate-cn
keepalive 10 120
comp-lzo
persist-key
persist-tun
verb 3
mute 20
client-cert-not-required
username-as-common-name
plugin /usr/lib/openvpn/openvpn-auth-pam.so openvpn

/etc/pam.d/openvpn :
auth optional pam_mysql.so user=dbuser passwd=dbpass host=localhost db=dbname table=dbtable usercolumn=login passwdcolumn=password where=active=1 sqllog=no crypt=4 verbose=0
account required pam_mysql.so user=dbuser passwd=dbpass host=localhost db=dbname table=dbtable usercolumn=login passwdcolumn=password where=active=1 sqllog=no crypt=4 verbose=0