Draw newton's fractal in F#

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F#

Bitmap

Hello, I am facing a problem with drawing Newton's fractal for f(x) = x^3 - 1 using F#
The problem is that my program seems to draw only the down right 1/4 of the fractal and nothing else. Since the actual drawn area is correct, I take it as the problem might be with the bitmap representation on the Form

Here's a link to the image I get
Imgur: The magic of the Internet[^]

What I have tried:

open System
open System.Drawing
open System.Windows.Forms
open System.Numerics

let pi = 3.14159265359
let MaxCount = 50
let multCol = 15
let Tol = 0.5
let r1 = Complex(1.0, 0.0)
let r2 = Complex(-0.5, sin(0.66*pi))
let r3 = Complex(-0.5, -sin(0.66 * pi))

let createImage () =
    let image = new Bitmap (800, 800,System.Drawing.Imaging.PixelFormat.Format32bppPArgb)
    let graphics = Graphics.FromImage(image)
    let mutable maxMod = 0.0
    for x = 0 to image.Width - 1 do
        for y = 0 to image.Height - 1 do
            let mutable z = Complex(float x , float y)
            let mutable count = 0
            while (count < MaxCount && Complex.Abs(z - r1) >= Tol && Complex.Abs(z - r2) >= Tol && Complex.Abs(z - r3) >= Tol) do
                if(Complex.Abs(z) > 0.0) then
                    z <- z - (z*z*z - Complex(1.0,0.0))/(Complex(3.0,0.0) * z * z)
                if(Complex.Abs(z) > maxMod) then
                    maxMod <- Complex.Abs(z)
                count <- count + 1
            let temp1 = Complex.Abs(z - r1)
            let temp2 = Complex.Abs(z - r2)
            let temp3 = Complex.Abs(z - r3)
            if(Complex.Abs(z - r1) <= Tol) then
                let Brush = new System.Drawing.SolidBrush(System.Drawing.Color.Red)
                graphics.FillRectangle(Brush, new Rectangle(x,y,1,1))
            if(Complex.Abs(z - r2) <= Tol) then
                let Brush = new System.Drawing.SolidBrush(System.Drawing.Color.Blue)
                graphics.FillRectangle(Brush, new Rectangle(x,y,1,1))
            if(Complex.Abs(z - r3) <= Tol) then
                let Brush = new System.Drawing.SolidBrush(System.Drawing.Color.Green)
                graphics.FillRectangle(Brush, new Rectangle(x,y,1,1))
    image.Save("redacted.png")

createImage()