Web Forms :: NotSupported Exception On Saving The Uploaded File?

I was so proud because I researched saving files and figured out how to extract the file name from what might be the full path. However, this doesn't work as I had expected. I still get the exception!

Here's the function that saves the file:

protected string SaveFile(HttpPostedFile file)
{
string savePath = Server.MapPath("~/Articles/");
string fileName = Path.GetFileName(article.FileName);
savePath += DateTime.Now.ToString();
savePath += " _ ";
savePath += fileName;
article.SaveAs(savePath);
return DateTime.Now.ToString() + " _ " + fileName;
}