Can't get monitor mode to work on a Broadcom card.

I like to monitor my network to make sure that there isn't any erroneous neighbors connecting to my wi-fi network, and I use Kismet for this purpose. I recently bought a new netbook computer, and when I try to run Kismet, I get an error saying that monitor mode could not be enabled. Here is the full error message:

unr3a1@Un341:~$ sudo kismet
[sudo] password for unr3a1:
Launching kismet_server: //usr/bin/kismet_server
Suid priv-dropping disabled. This may not be secure.
No specific sources given to be enabled, all will be enabled.
Non-RFMon VAPs will be destroyed on multi-vap interfaces (ie, madwifi-ng)
Enabling channel hopping.
Enabling channel splitting.
NOTICE: Disabling channel hopping, no enabled sources are able to change channel.
Source 0 (wireless): Enabling monitor mode for b43 source interface eth1 channel 6...
FATAL: Failed to set monitor mode: Invalid argument. This usually means your drivers either do not support monitor mode, or use a different mechanism for getting to it. Make sure you have a version of your drivers that support monitor mode, and consult the troubleshooting section of the README.
Done.
unr3a1@Un341:~$

I have tried to install the b43 driver firmware using b43-fwcutter, but that has not worked either. Here is the type of network card that I have (lspci -nn):

Network controller [0280]: Broadcom Corporation BCM4312 802.11b/g [14e4:4315] (rev 01)

Please take note, that the card functions for everything. I can browse the web, play online games, chat on AIM. This is not an issue connecting to the internet through my wireless card. This is a problem with enabling the monitor mode on the card. Any ideas as to what I can do to get monitoring to work on this card? Thanks.