Saving Image in ASP.NET

Hi,
I'm new to asp.net. I'm trying to save an image that I get from an URL, but I keep on getting this error message: A generic error occurred in GDI+. Below is my code:

private void BtnDownload_Click(object sender, System.EventArgs e)
{
string ImgName = ImagePic.ImageUrl;

StreamReader sr2 = new StreamReader(System.Net.WebRequest.Create(ImgName).GetResponse().GetResponseStream(),System.Text.Encoding.Unicode,true,100000);

System.Drawing.Image.FromStream(sr2.BaseStream).Save(Server.MapPath(@"../Directory"),System.Drawing.Imaging.ImageFormat.Jpeg);
}
I've set permission to read and write on the Directory folder.

Actually what I want to do is to enable the user to save the picture ImagePic.ImageUrl to a local directory. I'm not really sure how to do it.
Help will be very much appreciated