dwepdump question

I'm running FreeBSD 4.6.2 on a Dell Latitude CPi laptop with a SMC 2632W
card.  dstumbler works well for me, and I can connect to APs, etc.  The
problem I'm having is with dwepdump.

If I try to run 'dwepdump wi0 logfile' without changing any settings
beforehand, I get this error "unable to open device for packet capture:
BIOCSETIF: wi0: Network is down".  The only way I've gotten dwepdump to work
is by running 2 commands first: 'ifconfig wi0 0.0.0.0' and then 'prism2ctl
wi0 -m'.  Does setting the IP to 0.0.0.0 limit or filter any packets that
dwepdump might pick up?

This "solution" works fine when testing on the AP I have at work.  It will
pick up many packets in an hour.  However, with my neighbor's Linksys AP, it
won't pick up any packets.  However, ethereal and tcpdump show many packets
going though (ethereal shows them as "malformed packets" of course, because
they are encrypted).  So why does ethereal and tcpdump show so many packets,
but dwepdump will pick up nothing?  dstumbler will pick up my neighbor's
Linksys AP, with quality:signal:noise around 33:60:27.  Any suggestions/help
would be greatly appreciated.

Thanks!
Aaron