NetUserChangePassword invalid parameter

I have a win7 box and a win2008r2 box.  Not sure if this is related to my problem, but the win2008r2 server has KB3177108 installed.  Win7 does not have this patch.

When I run this program on Win7, it works (returns status_success and changes the password).  When I run this on win2008r2, it fails with error 87 - invalid parameter, but it also successfully changes the password...
What am I doing wrong here?

Thanks for looking at this...

#include "windows.h"
#include <LM.h>
#include <stdio.h>

int wmain(int argc, wchar_t * argv[])
{
    DWORD    error = NetUserChangePassword(
                L"mydomain",
                L"lowlyuser",
                L"oldpassword",
                L"newpassword"
                );

    wprintf(L"Error = %d\n", error);

    return error;
}