ColorMatrix non funzionante

    PrivateSub TsImConvertNeg_Click(ByVal sender As System.Object,    ByVal e As System.EventArgs) Handles TsImConvertNeg.Click

   If ImmCorrente IsNothingThenExitSub

   undoImage = CType(ImmCorrente.Clone, Image)

   MenuMAnnulla.Enabled = True

   ' conversione negativo

Dim cm As ColorMatrix = New ColorMatrix(NewSingle()() _

                       {NewSingle() {-1, 0, 0, 0, 0}, _

                        NewSingle() {0, -1, 0, 0, 0}, _

                        NewSingle() {0, 0, -1, 0, 0}, _

                        NewSingle() {0, 0, 0, 1, 0}, _

                        NewSingle() {0, 0, 0, 0, 1}})

        Ridisegna(cm)

    End Sub

    '''

  PrivateFunction Ridisegna(ByVal cm As ColorMatrix) AsBoolean

   Try

     Dim bmp AsNew Bitmap(ImmCorrente)

     Dim rc AsNew Rectangle(0, 0, ImmCorrente.Width,          ImmCorrente.Height)

     Dim mGrafic As Graphics = Graphics.FromImage(bmp)

' associare l'oggetto ColorMatrix a un oggetto ImageAttributes

     Dim imgattr AsNew ImageAttributes()_

            imgattr.SetColorMatrix(cm)

     'applicare ColorMatrix

   mGrafic.DrawImage(bmp, rc, 0, 0, ImmCorrente.Width, _

   ImmCorrente.Height, GraphicsUnit.Pixel, imgattr)

            ImmCorrente = bmp

            Zoom(FatZoom)

            mGrafic.Dispose()

            mClos = True    ' richiesta salvataggio

            ReturnTrue

        Catch ex As Exception

    Messaggi.Errore(mClassName, _   System.Reflection.MethodBase.GetCurrentMethod(), ex)

            ReturnFalse

        EndTry

    EndFunction