"assuming the servlet is configured properly" code example

Example: "assuming the servlet is configured properly"

Given following form:
<form action="register.do">
  <input type="text" name="Name">
  <input type="submit" value="Save"> 
</form>

and a servlet code:
public class RegisterServlet extends HttpServlet{
  pulic void doPost(HttpServletRequest req, HttpServletResponse res) {
  // registration logic goes here
  return;
}
}

With the above code, assuming the servlet is configured properly and registration logic works good, trying to register user fails. 
Choose one reason.