Problems linking to known WiFi network

Hi we have an IPad 2 with 3G. Currently traveling a lot and mainly using 3G.

Now house sitting where there is a wifi that we have used without difficulty previously. Now having returned to this home we find that although the Wifi network is named and listed we can not access. Wifi button is ON. Ask to Join is ON. If on screen where is option CHOOSE A NETWORK if select OTHER can enter network name for this home that is known to us. Default seems to be NONE for security. Tried to enter known password under various WEP and. WPA settings without success.

Tried complete shutdown and reset. Have updated sometime ago to IOS5 and seems to be running fine. 3G is working fine. Airplane mode set to off. Wifi lists as Not Connected. Not keen to use restore option.

Any ideas welcome. Thanks Max