Help with deauthentication attack.

I have a toshibsa satellite with an atheros card. I am using linux Backtrack a slaxware distro. The atheros works great for capture and recon using kismet. How ever I can not force a client to deauthenticate.

So I bought a second wireless card a 2511 EXT Prism 2.5 chipset. I thought this would solve my problems for sure but I can not set the mode to master.

My goal is to get ARP's. I am performing the capture and and stimulating from the same computer.

Is it possible to do both with the same card?

I am not too familiar with how the drivers work for these cards and the mode setting if anybody has anything to offer that may help I would appreciate it.

Thanks