ArgumentException - Le paramètre n'est pas valide

Bonjour, j'utilise ce code pour redimensionner une image et lui appliquer un filtre d'interpolation mais j'obtiens cette erreur sur chaque paramètre de pixelformat que je définis au moment de la création du BitMap.

Code:

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Private Function ScaleByPercent(ByVal Img As Image, ByVal Percent As Integer) As Image
 
        Dim nPercent As VariantType = Percent / 100
 
        Dim sourceWidth As Integer = Img.Width
        Dim sourceHeight As Integer = Img.Height
        Dim sourceX As Integer = 0
        Dim sourceY As Integer = 0
 
        Dim destWidth As Integer = (sourceWidth * nPercent)
        Dim destHeight As Integer = (sourceWidth * nPercent)
        Dim destX As Integer = 0
        Dim destY As Integer = 0
 
        Dim bm As Bitmap = New Bitmap(destWidth, destHeight, PixelFormat.Format24bppRgb)
        bm.SetResolution(Img.HorizontalResolution, Img.VerticalResolution)
 
        Dim gr As Graphics = Graphics.FromImage(bm)
        gr.InterpolationMode = InterpolationMode.HighQualityBilinear
 
        gr.DrawImage(Img, New Rectangle(destX, destY, destWidth, destHeight), New Rectangle(sourceX, sourceY, sourceWidth, sourceHeight), GraphicsUnit.Pixel)
        gr.Dispose()
        Return bm
 
    End Function

Merci de votre aide