DeviceIoControl失败，GetLastError()返回87，求高手解答！！！

DWORD dwNum, dwOut = 4, dwOutRet;
HANDLE hDriver = CreateFile(".//EnumProcess.sys",
GENERIC_READ | GENERIC_WRITE,
0, 
NULL, 
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL,
NULL);
if(INVALID_HANDLE_VALUE == hDriver)
{
MessageBox("CreateFile failed!");
return FALSE;
}
//获取进程个数
BOOL bOk = DeviceIoControl(hDriver,
IOCTL_NUM,
NULL, 0,
&dwNum,
dwOut,
&dwOutRet,
NULL);

bOk一直为FALSE， GetLastError()返回87，一直弄不明白，请高人指教小弟！
[解决办法]
该回复于2012-08-11 12:18:02被版主删除