Why am I getting null value for GetEl() function in PW

Hi,

Can anyone please help me with this code? I do not understand why am I getting null value for GetEl() function?

if (typeof (SiebelAppFacade.sw_member_role_PW) === "undefined") {

SiebelJS.Namespace("SiebelAppFacade.sw_member_role_PW");

define("siebel/custom/sw_member_role_PW", ["siebel/pwinfra"],

  function () {

   SiebelAppFacade.sw_member_role_PW = (function () {

    function sw_member_role_PW() {

     SiebelAppFacade.sw_member_role_PW.superclass.constructor.apply(this, arguments);

    }

    SiebelJS.Extend(sw_member_role_PW, SiebelAppFacade.DropDownPW);

    sw_member_role_PW.prototype.ShowUI = function (control) {

         SiebelAppFacade.sw_member_role_PW.superclass.ShowUI.apply(this, arguments);

        var el = this.GetEl();

     if(el && el.length){