Please check that your wireless router is close enough to your WLAN adapter. The range of the WLAN adapter can be reduced significantly by obstructions containing metal (e.g. reinforced walls).
Also check that the router is not set to use Wi-Fi channels 12 or 13 on your router’s setup page (ref. your router’s manual). The WLAN adapter does not support the use of Wi-Fi channels 12 and 13. If the router is set to Wi-Fi channel 12 or 13, change the router settings so another Wi-Fi channel is used within the range 1-11.