UDP Server & Client -- Server is not saving packets!

I am experimenting with transferring files within a LAN by UDP. I know that UDP has issues with reliability, but at the present time, this is just an experiment and sort of a proof-of-concept.

On Computer1, I'm Using Visual Studio 2012, and have the following code as a "UDP Client"

Code:

---

Imports System.Net
Imports System.Net.Sockets
Imports System.Text
Imports System.IO

Public Class Form1
    Private Sub ButtonSend_Click(sender As Object, e As EventArgs) Handles ButtonSend.Click
        Dim udp_Client As System.Net.Sockets.UdpClient
        Dim fStream As FileStream

        fStream = File.OpenRead("C:\Users\Computer1\Desktop\tempzip.zip")
        Dim fileBytes(fStream.Length) As Byte
        fStream.Read(fileBytes, 0, fileBytes.Length)

      udp_Client = New Sockets.UdpClient()
      udp_Client.Send(fileBytes, fileBytes.Length, "192.168.100.40", 5555)
    End Sub
End Class

---

On Computer2, also using VS 2012, I am using the following as a "UDP Server"

Code:

---

Imports System.Net
Imports System.Net.Sockets
Imports System.Text
Imports System.Threading
Imports System.IO

Public Class Form1
    Dim IP As String = "192.168.100.50"
    Dim Port As Integer = 5555
    Dim listenerThread As Thread
    Dim udp_Client As UdpClient

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        listenerThread = New Thread(AddressOf Listen)
        listenerThread.Start()
    End Sub

    Public Sub Listen()
        udp_Client = New UdpClient(Port)
        Dim clientThread As Thread = New Thread(New ThreadStart(AddressOf ThreadPacket))
        clientThread.Start()
    End Sub

    Public Sub ThreadPacket()
        Dim fStream As FileStream
        fStream = File.Create("C:\Users\Computer2\Desktop\UDPServer\tempzip.zip")

        While True
            Dim message As Byte() = udp_Client.Receive(New IPEndPoint(IPAddress.Parse(IP), Port))
            fStream.Write(message, 0, message.Length)
            LabelStatus.BackColor = Color.Yellow 'the label does turn yellow after I send a file from Computer1
        End While
    End Sub
End Class

---

When I click on the send button in Computer1, it should send the file tempzip.zip to Computer2. I have WireShark on both computers and can see that the packets are successfully sent from Computer1/UDPClient and are reaching Computer2/UDPServer. (As I noted in a comment toward the end of the code for the UDPServer, the filestream appears to be getting data.)

The problem is that tempzip.zip on Computer2/UDPServer (at C:\Users\Computer2\Desktop\UDPServer\tempzip.zip) is always empty.
I have tried this same setup with a simple text file of only 14 bytes, and the problem is the same. The packets are received, but nothing is written to the file on Computer2.

After spending the better part of this afternoon trying to find a solution, I still can't understand what the problem is. Does anyone have any ideas?