WLAN problem with two QNX6.3.2 machines and one XP

I installed the Orinoco 802.11b card on three QNX632 machines independently. I started the orinoco pccard via "mount -o channel=11,network=work,mode=adhoc -T io-net devn-orinoco.so " and assigend the ip addr as, 1.2, and 1.10(on XP machine), respect. However, i could ping thru btw 1.2 and 1.10, and 1.1 and 1.10. But it failed when tried to ping btw 1.1 and 1.2, and only occasional times succeeded.

I am now wondering if this is due to the adhoc network property or any other possible reasons. Really appreciate your ideas. Thx.