Description of problem:
I try to forward ports

Version-Release number of selected component:
firewall-config-0.3.5-1.fc19

Additional info:
reporter:       libreport-2.1.8
cmdline:        /usr/bin/python /usr/bin/firewall-config
executable:     /usr/bin/firewall-config
kernel:         3.11.1-200.fc19.i686
runlevel:       N 5
type:           Python
uid:            1000

Truncated backtrace:
firewall-config:1644:onChangeZone:TypeError: 'NoneType' object is not iterable

Traceback (most recent call last):
  File "/usr/bin/firewall-config", line 1644, in onChangeZone
    for item in sources:
TypeError: 'NoneType' object is not iterable

Local variables in innermost frame:
masquerade: False
name: 'time-exceeded'
_services: []
sources: None
default: False
_icmpblocks: []
interfaces: ['p2p1']
args: (<TreeSelection object at 0x9e64e14 (GtkTreeSelection at 0x9c04a50)>,)
iter: None
self: <__main__.FirewallConfig object at 0x9a1c66c>
item: 'p2p1'
builtin: False
icmpblocks: []
rules: []
services: ['dhcpv6-client', 'mdns', 'samba', 'ssh', 'vnc-server']
active_zone: 'public'
ports: [['80', 'tcp'], ['1900', 'udp'], ['8080', 'tcp'], ['39977', 'udp'], ['8200', 'tcp'], ['3128', 'tcp']]
forward_ports: []