C＃如何在while循环中从另一个类调用void方法

所以我有2个类别：ImageScanner和Form1

我想做的是继续在我的while循环中调用ScreenCapture方法，直到满足特定条件为止。此方法捕获我的屏幕，并将屏幕截图另存为PNG文件在同一位置。这意味着每次我截图时，新的都会替换旧的。

当我单击表单上的按钮时，我正在尝试执行此操作，因此我不知道为什么C＃给我一个错误。但是，当不在循环中时，我可以调用ScreenCapture方法。

class ImageScanner
    {
        public static void ScreenCapture()
        {
            var bmpScreenshot = new Bitmap(Screen.PrimaryScreen.Bounds.Width,
                                           Screen.PrimaryScreen.Bounds.Height,
                                           PixelFormat.Format32bppPArgb);

            // Create a graphics object from the bitmap.
            var gfxScreenshot = Graphics.FromImage(bmpScreenshot);

            // Take the screenshot from the upper left corner to the right bottom corner.
            gfxScreenshot.CopyFromScreen(Screen.PrimaryScreen.Bounds.X,
                                        Screen.PrimaryScreen.Bounds.Y,
                                        0,
                                        0,
                                        Screen.PrimaryScreen.Bounds.Size,
                                        CopyPixelOperation.SourceCopy);

            // Save the screenshot to the specified path that the user has chosen.
            bmpScreenshot.Save("Screenshot.png", ImageFormat.Png);
        }
    }



public partial class ClickForm : Form
{
    private void ECFile_Click(object sender, EventArgs e)
    {
        int j = 0;

        while (j < 20)
        {
            j += 1;
            ImageScanner.ScreenCapture();
        }
        MessageBox.Show("found");
    }
}

错误信息：

System.Runtime.InteropServices.ExternalException (0x80004005): A generic error occurred in GDI+.
   at System.Drawing.Image.Save(String filename, ImageCodecInfo encoder, EncoderParameters encoderParams)
   at System.Drawing.Image.Save(String filename, ImageFormat format)
   at AutoClicker.ImageScanner.ScreenCapture() in C:\Users\User1\source\repos\AutoClicker\AutoClicker\ImageScanner.cs:line 32
   at AutoClicker.ClickForm.ECFile_Click(Object sender, EventArgs e) in C:\Users\User1\source\repos\AutoClicker\AutoClicker\Form1.cs:line 232
   at System.Windows.Forms.Control.OnClick(EventArgs e)
   at System.Windows.Forms.Button.OnClick(EventArgs e)
   at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
   at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.ButtonBase.WndProc(Message& m)
   at System.Windows.Forms.Button.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)