Thread bug of BDB example of Win32

Hi,
I find one bug of BDB example of Win32.

Entironment:
OS:Win2000
BDB:4.4.16
Compiler:VC6+sp6

The example locate \\BDB_dir\\examples_cxx\txn_guide.The program define
one Marco
#define thread_join(thr, statusp)
\
((WaitForSingleObject((thr), INFINITE) == WAIT_OBJECT_0) &&
\
GetExitCodeThread((thr), (LPDWORD)(statusp)) ? 0 : -1)
to check if the thread exit normallly.

In main() function use the Marco as below
(void)thread_join(writerThreads[i], NULL);
The second parameter can't be NULL,with NULL the GetExitCodeThread()
will throw one exception for invalid address access.

After I use the Marco like this
DWORD exidcode=0;
(void)thread_join(writerThreads[i], &exidcode);
The threads work well.

Thanks
Sky