DSL Embedded :: Unable to put atheros-chpst card in ad-hoc mode

I am trying to use my atheros chipset based TL-550G(TP-Linlk WN-550G) along with my SBC. I tried with DSL embedded 3.2.tar.gz, I was very happy to see the card getting detected unfortunately I am unabel to put my card in ad-hoc mode whereas default "Managed mode" is being supported .Is this because of madwifi driver???

Can anyone suggest me how to overcome this problem.

this is the command which I tried

ifconfig ath0 192.168.1.234 netmask 255.255.255.0 up
iwconfig ath0 essid mesh channel 11 mode ad-hoc key off

the o/p error is

error for wireless request "Set Mode"(8B06)
SET failed on device ath0: invalid argument

original here.