Not pcking up some messages

Hi,
I am using the CSocketFile class along with CArchive. The problem that I am having is that messages are being sent to me (I checked with Ethereal about this), but I am apparently not picking up some messages. For example, I'll get the first message sent to me, but not any subsequent messages. I've seen topics on other boards about this scenario, and their solution is to do only one read, which isn't applicable in my scenario, because I want to first read in a header that has the message length, and based on that read more data. The header and data are sent as one packet, like a TCP packet. I have a onReceive function:

Code:

void A::OnReceive(int nErrorCode)  // A is derived from CSocket
{
	// TODO: Add your specialized code here and/or call the base class	
	ReadMessage(ar_read);
}

And here is my ReadMessage code:

Code:

void B::ReadMessage(CArchive &ar)
{
	uchar header[4];
	uchar buf[100]

	if(!ar.IsLoading())
	{
		ar.Read(header, 4);
		ar.Read(buf, header[1]); // header[1] is the length
	}
}

My program isn't crashing. Any idea why my messages are not being picked up?

Thanks.

I want to add this does not happen all the time. But after getting many messages, I do not get any subsequent messages.

I changed the ReadMessage() function, but still no luck:

Code:

void B::ReadMessage(CArchive &ar)
{  
        uchar header[4];
        uchar buf[100]

	if(ar.IsLoading())
	{
		do
		{
			ar.Read(header, 4); 
			ar.Read(buf, header[1]); // header[1] is the length
        	} while(!ar->IsBufferEmpty());
	}
}

Instead of treating the data as a stream, I treated the data coming in as a buffer, and everything appears to work fine; I did a Receive() call in the OnReceive function. I'm not convinced that this actually works. Any idea why treating the socket data as a block of data would work? When I was testing with another PC program everything worked fine, but when I tested with the actual hardware, I had these problems.
However, in the code that sends the data to the server, I treat the message as a stream even though I do only one Write() call.