WBMP to PNG error in some pixels in the final png

Question

I have a problem with my code. After read wbmp data, get width & height, I setPixel according to the data converted into the biarray. But my final png file contains a picture that looks like a supposed picture but some pixels are not properly places. (Please assume the width is always multiples of 8, ie exact x byte, so the padding zeroes can be disregarded)

My guess is my code is wrong or some error occurred when I read/convert the data.

I have spent hours to find the cause but couldnt do so. You guys might help me out.

Followings are my code:

using System;
using System.Drawing;
using System.IO;
using System.Collections;

class Program
{
    static void Main(string[] args)
    {

    BinaryReader binReader = new BinaryReader(File.Open(args[0], FileMode.Open));
    byte[] aa = new byte[1000];

    int width, height;

    try
    {
        //read the bytes until the end of stream
        for (int i = 0; i<aa.Length; i++)
        {
            aa[i] = binReader.ReadByte();
        }

    }
    catch (EndOfStreamException)
    {
        Console.WriteLine("End of the Stream");
    }
    //once end is reached,
    finally
    {
        width = aa[2];
        height = aa[3];

        Console.Write("Width: " + width);
        Console.Write(" Height: " + height + "\n");

        //Conversion
        BitArray bits = new BitArray(aa); //convert bytes array to bit array
        //Conversion Ends

        Bitmap image = new Bitmap(width, height);

        int index = 32;

        for (int r = 0; r < height; r++)
        {
            for (int c = 0; c < width; c++)
            {
                if (bits[index] == false)
                {
                    image.SetPixel(c, r, Color.Black);
                    index++;

                }
                else
                {
                    image.SetPixel(c, r, Color.White);
                    index++;
                }

            }
        }
        String n = "aa";
        image.Save(n + ".png", System.Drawing.Imaging.ImageFormat.Png);


    }

    Console.Write("\nPress any key to continue . . .");
    Console.ReadKey(true);
    }


}