I use Kubuntu 9.10 on an Asus F6Ve (Intel WiFi Link 1000bgn and module iwlagn) and had the same problem with knetworkmanager. I replaced it with nm-applet but, while better with network-manager-vpnc than knetworkmanager, it didn't connect either.
So I tried to force scanning of my particular hidden ssid (let's call it "whereRU") with :
I use Kubuntu 9.10 on an Asus F6Ve (Intel WiFi Link 1000bgn and module iwlagn) and had the same problem with knetworkmanager. I replaced it with nm-applet but, while better with network- manager- vpnc than knetworkmanager, it didn't connect either.
So I tried to force scanning of my particular hidden ssid (let's call it "whereRU") with :
-----8< ------- ---8<-- ------- -8<---- ------8< ------- ---8<-- --- ------- ---8<-- ------- -8<---- ------8< ------- ---8<-- ---
sudo iwlist wlan0 scan essid whereRU
-----8<
and ... after a few seconds... tada... IT WORKS !
and with knetworkmanager too.
I suppose iwlagn can't find a hidden ssid until you put its nose ON it ;-)
Hope this helps
Yfff