missing files in HttpContext.Current.Request.Files when i click button events in server side.

When i trace input files in client side after chose files, there are files in this input ($('#inputid')[0].files). And then, after click events in server side, missing request files. PS: I create input elements dynamic. Let me know why missing files.

 HttpFileCollection hfc = HttpContext.Current.Request.Files;
            for (int i = 0; i < hfc.Count; i++)
            {
                HttpPostedFile hpf = hfc[i];
            } code here