Loosing ESSID if WEP Key is set (I get crazy here at home)

Hi all Linux Friends,

i use a simple Wifi Solution at home. Everything is working on Windows XP Systems (1xLaptop + WG511v2 / 1xWorkst. + USB D-link DWL-G122 / AP DL-624+)
All machines are working fine together with or without 128bit WEP encryption.

Now I try to get work my Wireless Card in the Laptop via Knoppix 3.9. I´ve got much helpfull information in that forum here. I am happy now to be able to enable the Netgear WG511v2 PCMCIA Adapter via ndiswrapper and XP Driver. The green LED is on. In the next Step i find the information about my AP by write "iwlist scanning"
Then i write "iwconfig wlan0 essid "XXXXX" and again "iwconfig" to verify if it works. (No WEP encryption enabled by router at this time!!!)
Then IP Adress and Gateway entry and i am able to ping my router. The connection is established fine.

NOW MY PROBLEM !

If i enable the 128bit WEP Key at my AP now, and make a "iwconfig wlan0 key XXXX-XXXX-XXXX-XXXX-XXXX-XXXX-XX" then i get the following.
If i make a "iwconfig" The ESSID setting is set somehow to No/ANY and i see the WEP Key and the connection is lost (GGrrrrrrr !)
If i try to make again "iwconfig wlan essid "XXXXX", it doesnt store the new information. I always see that Fucking "No/ANY" at ESSID.

I only can restart and begin new. I do that for 3 Days and Nights now and the hair on my head get less and less. Maybe someone of you can help me please and tell me what i am doing wrong.

BR

Zett