Problem in downloading file from the server

[MuhammadTariq]

HI all,
I have a problem while downloading a file from the
server in a dot net web application.
The file downloads successfully,but some html of an
another page is appended at the end of the file.

HERE IS THE CODE FOR DOWNLOADING:

if ( Request.QueryString["qsFileName"]!= null )

{

mFileName = Request.QueryString["qsFileName"];

Page.RegisterStartupScript("CloseMe", "<script> window.close(); </script>");

Response.AppendHeader("content-disposition", "attachment;filename=" +
mFileName);

Response.WriteFile(@Server.MapPath(Request.ApplicationPath +
"/Attachments/") + mFileName);

}

do any body has some idea?????
Thanks in advance.

Regards Tariq.