[Discuss-gnuradio] one odd thing about bbn802.11b with USRP2_version

I have two USRP2 board  which I'm running under Ubuntu 10.04.Now I want to test it using the bbn 802_11b

 usrp2_version.I use the example scripts: 

bbn_80211b_rx.py and bbn_80211b_tx.py