How to see the packet flowing to/from NIC using PassThru?

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Hi! experts!

I'm really new about device driver and trying to be intermediate
between the WinSock and NIC to grab packets and manipulate them.
So I come to decide to work on Windows Server 2003 DDK and build the
PassThru sample inserting my DBGPRINT at the begining of PtReceive()
function to see the size of each packets for test.
And I installed the .sys file according to the PassThru
help(PassThru.htm) using .INF file.
After that, I use DebugView.exe which is able to show the debug
messages and I find some message is shown during my installation the
driver.
But I can't find my debug strings at all when I use InternetExploer to
get some page from web.

Any ideas?

Thanks.
.