File upload after dropdown selected

I have a Dropdown list & file uploader.Here i need, when dropdown list selected & after that need to load the file uploader.In my coding always it shows there's no File. Here i need SelectedValue passes to the database with file uploader.
My Code
protected void drpuser_SelectedIndexChanged(object sender, EventArgs e) { Guid SelectedUserId =Guid.Parse(drpuser.SelectedValue); FileUploader(); } FileUploader
public void FileUploader() { // var user = Membership.GetUser(); if (Roles.IsUserInRole("Administrator")) { Guid SelectedUserId = Guid.Parse(drpuser.SelectedValue); //<-- value correct foreach (string s in Request.Files) { HttpPostedFile file = Request.Files[s]; int fileSizeInBytes = file.ContentLength; string fileName = file.FileName; string fileExtension ...