netstat -s -u does not display UDP stats

Hi all,

I am performing a simple UDP performance test on two server systems.
They have identical Linux versions running.

2.6.18-1.2798.fc6 #1 SMP Mon Oct 16 14:39:22 EDT 2006 x86_64 x86_64
x86_64 GNU/Linux

Using the same piece of code I listen on UDP sockets on both systems.
I use SmartBits to pump UDP traffic for that port to both . I observe
the 'netstat -u -s' count incrementing based on the incoming traffic
on one of the system but the same smartbits when hooked up to the
second system doesn't refelect in an increment of 'netstat' counters.
I need to find at what point UDP packets start getting dropped and
this 2nd system behaving differently has perplexed me.

I made sure of the following :

1. Ran tcpdump and the 2nd system is receiving UDP packets for the
port I am listening on. (Also with right IP addresses)
2. The Rx packet count in the 'ifconfig eth0' output is incrementing.

Anything obvious I should check ? What might I be missing.

Thanks!