Pinging router problem on uCLinux platform

I am working on ea-LPC1788 board on uCLinux platform. I have configured the network using

1> ifconfig eth0 100.101.111.225 netmask 255.255.255.0 up
2> route add default gw 100.101.111.111 eth0

After that I connected to my host pc, which IP is 100.101.111.235, it with ping successfully and host pc can ping the board successfully. Host ip is 100.101.111.235.

means:

ping 100.101.111.235 is working on board and ping 100.101.111.225 is working on host pc successfully.

And also host pc can ping the router i.e. ping 100.101.111.111.
64 bytes from 100.101.111.111: icmp_req=1 ttl=64 time=21.5 ms
64 bytes from 100.101.111.111: icmp_req=2 ttl=64 time=6.05 ms
64 bytes from 100.101.111.111: icmp_req=3 ttl=64 time=6.25 ms

But when I have connected board via router, it will not ping router from the board i.e. ping 100.101.111.111, it will not work. After pressing ctrl+C I got.
PING 100.101.111.111 (100.101.111.111): 56 data bytes
^C
--- 100.101.111.111 ping statistics ---
7 packets transmitted, 0 packets received, 100% packet loss

This board cannot connect to any pc via router where as all pc are connected to each other via this router and working properly except this board.

I have checked the router table: route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
100.101.111.0 * 255.255.255.0 U 0 0 0 eth0
default 100.101.111.111 0.0.0.0 UG 0 0 0 eth0

It will very grateful if someone can help me.