Что не так с моим кодом? Vb.net

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привет всем я так запутался у меня есть этот код :

Dim LimitReached As Boolean = Me.InvokeIfRequired(Function() ProgressBar1.Value = ProgressBar1.Maximum)

'Keep looping until limit is reached.
While Not LimitReached

    'InvokeIfRequired() can take multiple lines.
    Me.InvokeIfRequired(
    Sub()
        ProgressBar1.Maximum = ListBox1.Items.Count.ToString() 'Calling ToString() is much better than Conversions.ToString().
        total.Text = ListBox1.Items.Count.ToString()
    End Sub) 'End of InvokeIfRequired().

    'Check if the limit is reached.
    LimitReached = Me.InvokeIfRequired(Function() ProgressBar1.Value = ProgressBar1.Maximum)

    If Not LimitReached Then

        Me.InvokeIfRequired(
        Sub()
            Try
                ListBox1.SelectedIndex = ListBox1.SelectedIndex + 1
                Label1.Text = ListBox1.SelectedItem.ToString
            Catch ex As Exception
            End Try
        End Sub)

        Try

            Me.InvokeIfRequired(
        Sub()
            ProgressBar1.Increment(1)
            detected.Text = Quarantine.ListBox2.Items.Count.ToString() 'Again, use .ToString(), not Conversions.ToString().
            Label5.Text = String.Format("{0:F2}%", ((ProgressBar1.Value / ProgressBar1.Maximum) * 100))
            files.Text = ProgressBar1.Value.ToString()
        End Sub)


            Dim SHA256 As New SHA256CryptoServiceProvider 'Shortened to "As New" instead of "As ... = New ..."

            'IMPORTANT: Wrap all streams in "Using .../End Using". This will ensure that the stream is closed and the file handle is released.
            Using f As New FileStream(ListBox1.SelectedItem, FileMode.Open, FileAccess.Read, FileShare.Read, 8192) 'Again, shortened to "As New".

                'REMOVED: You were setting "f = New FileStream..." two times. Not a good thing to do.
                SHA256.ComputeHash(f)
                Dim hash As Byte() = SHA256.Hash
                Dim buff As New StringBuilder '"As New".
                'This line is irrelevant: "Dim hashByte As Byte".
                For Each hashByte As Byte In hash
                    buff.Append(String.Format("{0:X2}", hashByte))
                Next


                Dim MyFilesList As String() = Directory.GetFiles(Application.StartupPath & "\Database\Sigs\Sha1\", "*.txt")
                Dim FoundedSearch As New List(Of String)()
                For Each filename As String In MyFilesList
                    Dim textFile As String = File.ReadAllText(filename)
                    If textFile.Contains(buff.ToString) Then
                        Me.InvokeIfRequired(Sub() f.Dispose())
                        Me.InvokeIfRequired(Sub() EncryptFile())
                        Me.InvokeIfRequired(Sub() Quarantine.ListBox2.Items.Add(ListBox1.SelectedItem()))
                        Me.InvokeIfRequired(Sub() WriteToLog("File Quarantined:" + ListBox1.SelectedItem))
                    End If
                Next

            End Using 'Close the FileStream.

        Catch ex As Exception
        End Try
    Else
        'REMOVED: "Timer1.Stop()" is no longer needed.

        Me.InvokeIfRequired(
        Sub()
            If CheckBox1.Checked = True Then
                System.Diagnostics.Process.Start("shutdown", "-s -t 00")
            Else
                ProgressBar1.Value = 0
                If ListBox1.Items.Count = 0 Then
                    If Form1.CheckBox1.Checked = True Then
                        full.CancelAsync()
                        quick.CancelAsync()
                        Critical.CancelAsync()
                        cust.CancelAsync()
                    End If
                Else
                    Form1.CheckBox1.Checked = False
                    Form1.CheckBox2.Checked = False
                    Form1.CheckBox3.Checked = False
                    Form1.CheckBox4.Checked = False
                    Quarantine.Label3.ForeColor = Color.DarkRed
                    Quarantine.Label2.ForeColor = Color.DarkRed
                    full.CancelAsync()
                    quick.CancelAsync()
                    Critical.CancelAsync()
                    cust.CancelAsync()

                End If
            End If
        End Sub) 'End of InvokeIfRequired().
    End If
    'Do some more background stuff...
End While

И

Dim SHA256 As New SHA256CryptoServiceProvider

был md5, и он работал и сканировал список хэшей md5, но теперь я хочу сделать sha256, и я использовал список хэшей sha256, и он не обнаруживает файл(файл-это тот же самый хэш, который я проверил с помощью virus total)

Что я уже пробовал:

как вы можете видеть выше, я попытался изменить его на sha256-единственное, что мне нужно изменить, но нет, не работает. :-(

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