No wireless network connection

I have tried to establish a wireless connection for a box in my lan in a inaccessible place for a wired connection.
I have used ndiswrapper and the win xp driver for my Siemens Gigaset 108 usb adapter. I succeeded to configure the connection using SSID and WPA-PSK key. The computer can see the network, My Speedtouch 780 modem can see the computer but says the connection is inactive. When I try to connect it keeps asking for my WPA key, although a 63 character key is filled in already. My real key consists of 10 characters. When I fill in my key, no connection is established and the window called: “wireless network secrets required” pops up again with a different 63 character key.
Who can help?