一个DS的问题！　

为什么SubmitUrb总是不能成功?
NTSTATUS USBDOGDevice::Write(KIrp I)
{
t << \"Entering USBDOGDevice::Write, \" << I << EOL;
// TODO: Check the incoming request.  Replace \"FALSE\" in the following
// line with a check that returns TRUE if the request is not valid.
NTSTATUS status = STATUS_SUCCESS;

KMemory Mem(I.Mdl()); // Declare a memory object
// Use the memory object to create a pointer to the caller\'s buffer
PUCHAR pBuffer = (PUCHAR) Mem.VirtualAddress();

ULONG   dwTotalSize = I.WriteSize(CURRENT);
ULONG   dwBytesSent = 0;

// TODO: If the write can be satisfied immediately, set the Information
// and Status fields now, then call NextIrp to complete this IRP
// and start processing the next IRP in the queue.
    PURB pUrb = m_Lower.BuildClassRequest(
pBuffer,          // TransferBufferMDL
dwTotalSize,        // TransferBufferLength=dwTotalSize
0, // RequestTypeReservedBits=0
0x09, //Request =0x09 just for the dog
0x0200, //Value =0x0200,for Unknow reason
FALSE, //BOOLEAN bIn=FALSE
FALSE, //BOOLEAN bShortOk=FALSE
NULL, //PURB Link=NULL
0, //UCHAR Index=0
URB_FUNCTION_CLASS_DEVICE, //USHORT Function=URB_FUNCTION_CLASS_DEVICE
NULL //PURB Link=NULL
);

    // Submit the URB to our USB device, synchronously
    if (pUrb != NULL)
    {
        status = m_Lower.SubmitUrb(pUrb, NULL, NULL,0);

        if ( NT_SUCCESS(status) )
        {
            dwBytesSent = pUrb->UrbBulkOrInterruptTransfer.TransferBufferLength;

        }
else
{
t<<\"SubmitUrb fialed  \\n \" ;

}

delete pUrb;
    }
else
{
t<<\"no enough resource by \\n \" ;
}

// TODO: If the device cannot accept all of the data yet, initiate a
// request to the physical device here, and defer the Information,
// Status, and NextIrp handling until the hardware indicates that
// the write is complete.  Typically, this might be handled in a
// DPC that is called after the hardware finishes transferring
// the data.

// TODO: To satisfy the write now, transfer data to the device
// from caller\'s buffer at \"pBuffer\".  Then, indicate how much
// data was transferred:

I.Information() = dwBytesSent;

return I.PnpComplete(this, status);

}