Problem accessing / pinging instances in VLAN Mode

Hi,
i have a problem accessing and pinging instances i created. I have ensured that the access is given to port 22 and icmp.
My setup:
i have all nova components installed on one single server.

nova.conf looks like this:
--sql_connection=mysql://root:nova@172.25.21.2/nova
--s3_host=172.25.21.2
--rabbit_host=172.25.21.2
--ec2_host=172.25.21.2
--verbose
--ec2_url=http://172.25.21.2:8773/services/Cloud
--network_manager=nova.network.manager.VlanManager
--fixed_range=10.0.0.0/24
--network_size=64
--dhcpbridge_flagfile=/etc/nova/nova.conf
--dhcpbridge=/usr/bin/nova-dhcpbridge
--logdir=/var/log/nova
--state_path=/var/lib/nova
--verbose

the network interfaces file looks like:

auto lo
iface lo inet loopback
auto br100
iface br100 inet static
address 172.25.21.2
netmask 255.255.255.0
broadcast 172.25.21.255
gateway 172.25.21.1
dns-nameservers 134.147.62.133
       bridge_ports eth1
       bridge_stp off
       bridge_maxwait 0
       bridge_fd 0

the output of ifconfig is:
http://paste.openstack.org/show/807/

when i use euca-run-instance....
the nova-network log shows that error :
http://paste.openstack.org/show/803/ <-- i think it shows an error accessing the database...

the get-console-output.. of the instance just created shows:
http://paste.openstack.org/show/806/

i dont know how to proceed from here ... would be great if someone can help me on this!
if u need further information, just ask.
greetz and thx ! jo.