I Get a undefined OnSuccess

I Get a undefined OnSuccess

Hello. 
I'm getting a Undefined value OnSuccess response and never fire a WebMethod.... (asp.Net vs2013, Framework 4.5 jquery 2.1.1)
This is MyCode:

  1. <script>
  2.         function fun() {
  3.             PageMethods.GetPageMethod(onSucceed, onError);
  4.             return false;
  5.         }
  6.         function onSucceed(result) {
  7.             alert(result);              // HERE I Get a long HTML as Server Response instead a "Welcome PageMethods" string
  8.         }                               // By the way, debugging never reach a breakpoint inside GetPageMethod 
  9.         function onError(result) {
  10.         }
  11.     </script>