Cannot Access IP Instances

I have Nova on my computer with one ethernetcard.I use FlatDHCP for network management.Installation process successfull and i can publish and run isntances.

I have network 10.0.0.0 as fixed_ip and netmask 255.255.255.240.

I have also config security group and allowing port 22 as ssh access and icmp port.

instances which running get ip 10.0.0.34 as like below when i excute nova-list :

############################################################
nova list
############################################################
+----+----------+--------+-----------------------------------------------------------+
| ID | Name | Status | Networks |
+----+----------+--------+-----------------------------------------------------------+
| 1 | Server 1 | ACTIVE | public_2=10.0.0.34; public_0=10.0.0.2; public_1=10.0.0.18 |
+----+----------+--------+-----------------------------------------------------------+

############################################################

But when i try to ping 10.0.0.34 and others ip.all of them are unreachable.

when i try to access isntances with vncviewer with command :

#vncviewer [ip_host]:[port]

i can access it, but when i execute ifconfig: it's appear instances dont get ip address from dhcp.Then i try to use "dhclient" but it's doesn't work

this is detail of ifconfig on my controller :

############################################################
ifconfig
############################################################

br100 Link encap:Ethernet HWaddr ae:f2:b7:90:36:ea
          inet addr:10.0.0.33 Bcast:10.0.0.47 Mask:255.255.255.240
          UP BROADCAST MULTICAST MTU:1500 Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)

eth0 Link encap:Ethernet HWaddr b8:ac:6f:1e:30:6f
          inet addr:192.168.2.55 Bcast:0.0.0.0 Mask:255.255.255.0
          inet6 addr: fe80::baac:6fff:fe1e:306f/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
          RX packets:2857 errors:0 dropped:0 overruns:0 frame:0
          TX packets:2724 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:2204585 (2.2 MB) TX bytes:519780 (519.7 KB)
          Interrupt:16

lo Link encap:Local Loopback
          inet addr:127.0.0.1 Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING MTU:16436 Metric:1
          RX packets:4649 errors:0 dropped:0 overruns:0 frame:0
          TX packets:4649 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:2643849 (2.6 MB) TX bytes:2643849 (2.6 MB)

virbr0 Link encap:Ethernet HWaddr 02:f3:f0:80:22:31
          inet addr:192.168.122.1 Bcast:192.168.122.255 Mask:255.255.255.0
          UP BROADCAST MULTICAST MTU:1500 Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:0 (0.0 B) TX bytes:0 (0.0 B

############################################################

############################################################
And this is detail of my nova.conf
############################################################

--dhcpbridge_flagfile=/etc/nova/nova.conf
--dhcpbridge=/usr/bin/nova-dhcpbridge
--logdir=/var/log/nova
--state_path=/var/lib/nova
--lock_path=/var/lock/nova
--force_dhcp_release=True
--use_deprecated_auth
--iscsi_helper=tgtadm
--verbose
--routing_source_ip=192.168.2.55
--sql_connection=mysql://nova:nova@127.0.0.1/nova
--libvirt_type=kvm
--glance_host=127.0.0.1
--image_service=nova.image.glance.GlanceImageService
--network_manager=nova.network.manager.FlatDHCPManager
--flat_network_dhcp_start=10.0.0.3
--flat_network_bridge=br100
--flat_injected=False
--fixed_range_v4=10.0.0.8
--network_size=8
--bridge_interfaces=br100

#########################################################

Help to solve this issue ?
what should i do ?

Thanks before