[Help] Does anyone use airlive x.usb(abgn,dual band,ar9170 chipset) for packet cap?

Dear all:
Thanks in advance.
Recently I installed kali 1.0.5 in vmware, and x.usb seems work well(plug n play).

root@kali:~# iwconfig
eth0 no wireless extensions.

eth1 no wireless extensions.

lo no wireless extensions.

wlan0 IEEE 802.11abgn ESSID:off/any
Mode:Managed Access Point: Not-Associated Tx-Power=20 dBm
Retry long limit:7 RTS thr:off Fragment thr:off
Encryption key:off
Power Management:off

root@kali:~# airmon-ng check kill

Found 4 processes that could cause trouble.
If airodump-ng, aireplay-ng or airtun-ng stops working after
a short period of time, you may want to kill (some of) them!
-e
PID Name
2405 dhclient
2479 NetworkManager
2529 dhclient
3610 wpa_supplicant
Killing all those processes...

root@kali:~# airmon-ng start wlan0


Interface Chipset Driver

wlan0 Atheros AR9170 carl9170 - [phy0]
(monitor mode enabled on mon0)

root@kali:/home/lxp/wf# airodump-ng -w 1.pcap --bssid 4C:E6:76:43:1D:9E -c 3 mon0

CH 3 ][ Elapsed: 24 s ][ 2013-10-10 16:31

BSSID PWR RXQ Beacons #Data, #/s CH MB ENC CIPHER AUTH ESSID

4C:E6:76:43:1D:9E -28 100 265 3347 3 3 63e OPN 4CE676431D9E

BSSID STATION PWR Rate Lost Frames Probe

4C:E6:76:43:1D:9E BC:CF:CC:B1:85:89 -73 0e- 5e 2 205 4C:E6:76:43:1D:9E 18:3D:A2:3E:BE:4C -127 0 - 0e 46 3196 4C:E6:76:43:1D:9E BC:CF:CC:B1:85:89 -72 0e- 2e 0 195

Things seems good, but lost almost all downlink(from ap to sta)packets in the file(1.pcap). RXQ is 100(stable), but still lost packet. The PWR of test STA is a little bit low(-127), and varies from -21 to -90 during sending packets. I tried many times, and got same result.

Does anyone have any ideas? Or is my x.usb not suitable for packet capturing under 802.11n?Thanks.

PS:
1 my integrated wifi intel 6200agn, ap mode n, channel 3, 20MHz, 1T1R;
2 it's good when ap is set to mode g;
3 it's not good when use HT(40MHz) either;