ok i have a alpha high power usb adaptor with 9db antenae and when i search for networks in my area using the windows program it came with i find around 6 or 7 networks - however when i run a scan in airodump-ng in backtrack it only finds one - mine - why would it not find the others it finds in windows?

obviously i am only searching for other networks out of interest and in no way intend trying to gain access using them