VB.NET - 奇怪的行为 - 定时器无法启动

Question

当我连接时，背景颜色变为“SpringGreen”，当发生Wxeption时，它们变为“黄色”，出现消息框（“Timer on”），背景颜色变为“Gray”？ ？

但当Exece发生在ReceiveMessag（）时，颜色变为“黄色”，调试行显示启用了trmReboot，但没有消息框，背景颜色也没有变为“灰色”????

为什么定时器不能以ReceiveMessag（）Exeption ??

开头

 Private Sub Connect()
    Try
        _client = New TcpClient(strIP, intPort)
        Threading.ThreadPool.QueueUserWorkItem(AddressOf ReceiveMessages)
        Try
            If _client.Connected Then
                login()
                tsStatusIP.BackColor = Color.SpringGreen
                tsStatusIPport.BackColor = Color.SpringGreen
                tsStatusIP.Text = "IP adres: " + strIP
                tsStatusIPport.Text = "Server poort nummer: " + intPort.ToString
                booConnected = True
            End If
        Catch ex As Exception
            'MsgBox(ex.Message)
        End Try
    Catch ex As Exception
        ExecptionHandler()
    End Try
End Sub
Private Sub ReceiveMessages(state As Object)
    Try
        While True
            Dim ns As NetworkStream = _client.GetStream()

            Dim toReceive(100000) As Byte
            ns.Read(toReceive, 0, toReceive.Length)
            Dim txt As String = Encoding.ASCII.GetString(toReceive)
            messagerecieved(txt)

            '  If Application.OpenForms().OfType(Of frmReceivedData).Any = True Then 'check if form is open
            If txtReceivedData.Visible = True Then
                txtReceivedData.Text = txtReceivedData.Text + txt
            End If
            '  End If
        End While
    Catch ex As Exception
        ExecptionHandler()
    End Try
End Sub
Private Sub ExecptionHandler()
    tsStatusIP.BackColor = Color.Yellow
    tsStatusIPport.BackColor = Color.Yellow
    booConnected = False
    tmrReboot.Enabled = True
    Debug.Print(tmrReboot.Enabled)
End Sub
Private Sub tmrReboot_Tick(sender As Object, e As EventArgs) Handles tmrReboot.Tick
    MsgBox("timer on")
    tsStatusIP.BackColor = Color.Gray
    tsStatusIPport.BackColor = Color.Gray
End Sub