Get RadCartesianChart from Grid (8x3) issue when organizing

im has a grid of 8x3 lines and col.below to get a RadCartesianChart and it creates an image on disk with the "ExportCHARTtoBMP" function

for (int row = 0; row < (chartgridimage.RowDefinitions.Count())-1; row++)
    for (int column = 0; column < chartgridimage.ColumnDefinitions.Count(); column++)
    {
        RadCartesianChart chart = chartgridimage.ChildrenOfType<RadCartesianChart>().FirstOrDefault(e => Grid.GetRow(e) == row && Grid.GetColumn(e) == column);
        chart.Measure(new System.Windows.Size(470, 280));
        chart.Arrange(new Rect(0, 0, 470, 280));
        ExportCHARTtoBMP(chart,"chart"+row+""+column);
    }

      

        
        
        
      

    

export to bmp func:

private void ExportGRIDtoBMP(Grid gridinput, string filename)
{
    gridinput.Measure(new System.Windows.Size(double.PositiveInfinity, double.PositiveInfinity));
    int grid1Width = (int)Math.Round(gridinput.ActualWidth);
    int grid1Height = (int)Math.Round(gridinput.ActualHeight);
    grid1Width = grid1Width == 0 ? 1 : grid1Width;
    grid1Height = grid1Height == 0 ? 1 : grid1Height;

    RenderTargetBitmap rtbmp = new RenderTargetBitmap(grid1Width, grid1Height, 96d, 96d, PixelFormats.Default);
    rtbmp.Render(gridinput);
    BmpBitmapEncoder encoder = new BmpBitmapEncoder();
    encoder.Frames.Add(BitmapFrame.Create(rtbmp));
    FileStream gridbmpfilestrm = File.Create(@"C:\Users\Admin\Desktop\" + filename + ".bmp");
    encoder.Save(gridbmpfilestrm);
    gridbmpfilestrm.Close();
    rtbmp.Clear();
}

      

        
        
        
      

    

The problem is that when the image is saved to disk, the series of lines changes.