path access denied

Good day 

please assisst i get the error access denied to the path, also note that i gave everyone full control rights on the folder. 

here is my code

if (e.CommandName == "Download")
                {
                    Response.Clear();
                    Response.ContentType = "application/octec-stream";
                    Response.AppendHeader("content-disposition", "filename" + e.CommandArgument);
                    Response.TransmitFile(Server.MapPath("~/POP") + e.CommandArgument);
                    Response.End();
                }