WiFi connectivity problem. please help!

Hi guys
I'm using an Arduino Yun . I'm not able to get the expected output for the example Wifi programs provided in my Sketch. My WiFi is not able to scan any other access points when i run the example program scan network. File-Examples-Wifi-ScanNetworks.

The Access point of Arduino Yun gets switched on and can connect other systems to it, but not able to connect Arduino to other access points.

Please provide me the solution if you have encountered same problem.

Thanks in advance.