at first: sorry for my bad english!

The Problem:
I have no access to my wlan modem (speedport W701V and AVM Fritzbox Phon Wlan) if I select the option "covered ssid" in the modem-config. 
knetworkmanager shows the network with signal-strenght = 0, connection is not working.

If I change the option to "uncovered ssid" in the modem-config, the connection works fine with full signal-strenght.

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My hardware (hwinfo): 
20: PCI 300.0: 0282 WLAN controller
  [Created at pci.301]
  UDI: /org/freedesktop/Hal/devices/pci_8086_4227
  Unique ID: y9sn.mAONicWAIr5
  Parent ID: qTvu.bQ30eTbcr+3
  SysFS ID: /devices/pci0000:00/0000:00:1c.1/0000:03:00.0
  SysFS BusID: 0000:03:00.0
  Hardware Class: network
  Model: "Intel Thinkpad  X60s, R60e model 0657"
  Vendor: pci 0x8086 "Intel Corporation"
  Device: pci 0x4227 "PRO/Wireless 3945ABG Network Connection"
  SubVendor: pci 0x8086 "Intel Corporation"
  SubDevice: pci 0x1011 "Thinkpad  X60s, R60e model 0657"
  Revision: 0x02
  Driver: "ipw3945"
  Driver Modules: "ipw3945"
  Device File: wlan0
  Features: WLAN
  Memory Range: 0xedf00000-0xedf00fff (rw,non-prefetchable)
  IRQ: 21 (no events)
  HW Address: 00:13:02:99:b2:a4
  Link detected: yes
  WLAN channels: 1 2 3 4 5 6 7 8 9 10 11 12 13 34 36 38 40 42 44 46 48 52 56 60 64 100 104 108 112 116 120 124
  WLAN frequencies: 2.412 2.417 2.422 2.427 2.432 2.437 2.442 2.447 2.452 2.457 2.462 2.467 2.472 5.17 5.18 5.19 5.2 5.21 5.22 5.23 5.24 5.26 5.28 5.3 5.32 5.5 5.52 5.54 5.56 5.58 5.6 5.62
  WLAN bitrates: 1 2 5.5 11 6 9 12 18 24 36 48 54
  WLAN encryption modes: WEP40 WEP104 TKIP CCMP
  WLAN authentication modes: open sharedkey wpa-psk wpa-eap
  Module Alias: "pci:v00008086d00004227sv00008086sd00001011bc02sc80i00"
  Driver Info #0:
    Driver Status: ipw3945 is active
    Driver Activation Cmd: "modprobe ipw3945"
  Driver Info #1:
    Driver Status: iwl3945 is not active
    Driver Activation Cmd: "modprobe iwl3945"
  Config Status: cfg=no, avail=yes, need=no, active=unknown
  Attached to: #5 (PCI bridge)
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System Info: #1
    Manufacturer: "LENOVO"
    Product: "946154G"
    Version: "ThinkPad R60"
    Serial: "L3A9470"
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