C# Record Screen, Parameter not valid

Question

I have recently tried to make a screen recorder, but i'm keep getting this error: "An unhandled exception of type 'System.ArgumentException' occurred in System.Drawing.dll" and the Additional Information: "Parameter not valid". This is the code i have so far:

`       
 private Bitmap captureScreen()
 {
     Size s = Screen.PrimaryScreen.Bounds.Size;
     Bitmap bm = new Bitmap(s.Width, s.Height);
     Graphics g = Graphics.FromImage(bm);
     g.CopyFromScreen(0, 0, 0, 0, s);
     return bm;
 }
 private void screenCapturer_Tick(object sender, EventArgs e) //timer
 {
     screenPreview.Image = captureScreen();
 }

`

The error occurs some time after the form has loaded. When i change the interval of the timer the error occurs later.

Thanks.