Strange wireless problem

[cmatrix]

hi all, after I installed Ubuntu 7 and logged in through the default GNOME session, I found Ubuntu automatically detected my wireless network and I only had to enter my wireless network key to be connected

After installing KDE, and logging using the KDE session I found that Ubuntu can see also my wireless network but I can't get connected! :(:(:(

So I used Wifi radar where I entered my Network key there, but whenever I click connect, it show me the screen Acquiring IP Address, then this screen goes and I am not connected...simply nothing happens :(

So can anyone please help me by telling me what I might be doing wrong? And how I can get connected to my wireless network from the KDE session?

Thanks in advance for your time