Problem with Wireless connection....

Hi All,

Problem is that i can not connect the laptop with wireless network. When i search for the avalible network it says " No wireless networks were found in range Make sure the wireless switch on your computer is on" i go to advanced configuration there i found that there is no "Wireless Network" tab. I search on google & found it is because of Wireless Zero Configuration services, i checked it was on, i restart and i can see the wireless network tab in properties, but still i can not connect to wirless network. What should i do to fix this problem.

Wireless drivers are installed properly.
We have many of these laptops they all are ghosted with same ghost only this laptop has problem.

Also at our client place i found same problem, they have 12 desktops added the Realtek wirless PCI card in it, the problem there was they can not connect any system to the wireless network. I went there and checked that it might be the channel problem i changed it but hope. Than i found some system does not have wireless network tab, same as above i checked Wirelss Zero Configuration services. In some system there was no wireless zero configuration services, i installed them manually but still no hope.  Can you please give some idea what should i do to fix that 2 problems????