Error while issuing ping command inside monkeyrunner script

Question

i am facing some issues in device.shell('ping -c 2 192.168.1.1') inside a monkeyrunner script. Its throwing below error:- 120202 20:12:17.192:S [main] [com.android.chimpchat.adb.AdbChimpDevice] Error executing command: ping -c 2 192.168.1.1

while (count<1000) :
device.shell('dmesg -c')
print '****swithing OFF wifi in loop NO-',count
device.touch(400,155,MonkeyDevice.DOWN_AND_UP)
time.sleep(10)
print '****switching ON wifi in loop NO-',count
device.touch(400,155,MonkeyDevice.DOWN_AND_UP)
time.sleep(25)
fd=open('pingstats.txt','a+b')
fd.write('***Loop-%i \n************\n%s\n****************\n' % (int(count),ping))
ping = device.shell('ping -c 2 192.168.1.1')
status=re.search('unreachable',ping)
if status:
    dmesg=device.shell('dmesg')
    fd.write(logcat)
fd.close()
count = count + 1

please see above script... Someone please help....