Destination Host Unreachable!!!!

hi every body

I want setup an ad-hoc wireless network between my PC (opensuse 11.2)
and my PDA (window mobile 6.1) .

after some search and try, I setup ad-hoc by yast network seting,
every thing is ok and I my PDA found PC essid and connet to it,
but nor PC and PDA can ping each other and ping command just say :
“Destination Host Unreachable”

I have a Linksys usb wifi adapter that correctly work in windows and
I can connect and ping and share.

opensuse find and work fine with my Linksys wifi adapter
(i can see with lsusb and ifconfig )

the route seems ok:

#route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface U 0 0 0 vmnet1 U 0 0 0 eth0 U 0 0 0 vmnet8 U 0 0 0 wlan0 U 0 0 0 eth0 U 0 0 0 lo UG 0 0 0 eth0

do i need change iptable or problem is other?