Datagridview not showing .bmp

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C#

DataGridView

-Two ListBoxes binded together. The first one to show a directory, and the second to show a subfolder.
-DataGridView to show the .bmp files.
I need to Set only one column called (Blocks) and add a double click event to insert the dwg file.
the red x is shown in datagridview

What I have tried:

private void Form1_Load(object sender, EventArgs e)
{
    listBox1.DataSource = Directory.GetDirectories(rootDirectory).Select(Path.GetFileName).ToList();
    listBox1.SelectedIndexChanged += ListBox1_SelectedIndexChanged;
    listBox2.SelectedIndexChanged += ListBox2_SelectedIndexChanged;

    DataGridViewImageColumn dgvimgcol = new DataGridViewImageColumn();
    dgvimgcol.ImageLayout = DataGridViewImageCellLayout.Stretch;
    dgvimgcol.Width = 250;
    dgvimgcol.HeaderText = "Blocks";
    dgvimgcol.Image = null;
    dataViewImages.RowTemplate.Height = 300;
    dataViewImages.Columns.Add(dgvimgcol);
    dataViewImages.AllowUserToAddRows = false;
    dataViewImages.AutoSizeColumnsMode = DataGridViewAutoSizeColumnsMode.Fill;
}


private void ListBox1_SelectedIndexChanged(object sender, EventArgs e)
{
    // When an item changes in the first listbox, update the second listbox datasource
    var parentDir = Path.Combine(rootDirectory, listBox1.SelectedItem.ToString());
    listBox2.DataSource = Directory.GetDirectories(parentDir).Select(Path.GetFileName).ToList();
}

private void ListBox2_SelectedIndexChanged(object sender, EventArgs e)
{
    // When an item changes in the second listbox, update the datagridview datasource
    var parentDir = Path.Combine(rootDirectory, listBox1.SelectedItem.ToString(),
    listBox2.SelectedItem.ToString());
    dataViewImages.DataSource = Directory.GetFiles(parentDir).Select(f => new { FileName = Path.GetFileName(f) }).ToList();
}