Channel problem with hostap

[David Goodenough]

I have a machine with hostap, using Senao cards.  There are two cards in the 
machine, and when I use iwlist wlan1 scan it finds (just) the partner (ad-hoc
mode) station and lists its channel (10).  I then try to set the card (using 
iwconfig) to channel 10, and it keeps resetting to channel 1.  

Is this likely to be a card problem, a software problem or a config problem?

Anyone got any ideas?  Thanks in advance

David