使用scan-wifi start-wifi指令，然后打印出的信息是这样
root@FriendlyARM /]# scan-wifi
cfg80211: Calling CRDA to update world regulatory domain
libertas_sdio: Libertas SDIO driver
libertas_sdio: Copyright Pierre Ossman
libertas_sdio mmc1:0001:1: (unregistered net_device): 44:39:c4:46:4d:24, fw 9.70
.3p36, cap 0x00000303
libertas_sdio mmc1:0001:1: wlan0: Marvell WLAN 802.11 adapter
usbcore: registered new interface driver ath9k_htc
usbcore: registered new interface driver rt73usb
usbcore: registered new interface driver rt2800usb
rtw driver version=v3.3.2_3192.20120103
usbcore: registered new interface driver rtl8192cu
usbcore: registered new interface driver zd1211rw
90% Tenda_195BC0 (Security)
74% 闄即鏄渶闀挎儏鐨勫憡鐧?(Security)
51% H3C-Network (Security)
100% fnmdx (Security)
100% lianbushang (Security)
84% Sirius (Security)
57% DPFWQ (Security)
7 Access Point Found
[root@FriendlyARM /]# start-wifi wpa lianbushang 18230344986
ieee80211 phy0: assoc: bss (null) not in scan results
ioctl[SIOCSIWESSID]: No such file or directory
[root@FriendlyARM /]# ieee80211 phy0: assoc: bss (null) not in scan results
cfg80211: Calling CRDA for country: JP
然后显示的是已经连接wifi，有的时候能ping通大多时候ping不同，，请问是什么原因
