how to use HttpQueryInfo in VB?

hi, experts,
I need to use HttpQueryInfo() to get back Http response information from server such as statuscode. I used the following code in VB as:

Dim dwStatus As String * 1024
Dim bRet As Boolean, dwLen As Long
dwLen = 1024
bRet = HttpQueryInfo(hHttpRequest, HTTP_QUERY_STATUS_CODE, dwStatus, dwLen, "")

but, I always got bRet = False. I'm sure the server-side code is correct to send back its response information. I guess the problem is the argument dwLen of DLL: HttpQueryInfo() because it needs a pointer in definition. From VB I can't find how to declare a pointer.

By the way, we use Wininet.dll in client/server codes under WinNT and ISAPI platform.

Does Any expert has answer or clue for the problem?

thanks in advance,