I'm trying to make Tampermonkey create an alert whenever this button is clicked:

<button id="main-sideline" class="awsui_button_vjswe_108wz_7 awsui_variant-normal_vjswe_108wz_27" type="submit">
<span class="awsui_content_vjswe_108wz_3">Sideline</span>
</button>

What could be wrong here please:

// ==UserScript==
// @name         New Userscript
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  try to take over the world!
// @author       You
// @require      https://cdnjs.cloudflare.com/ajax/libs/jquery/3.5.1/jquery.min.js
// @match        https://databee.com
// @icon         https://www.google.com/s2/favicons?domain=amazon.dev
// @grant        none
// ==/UserScript==

(function() {
    'use strict';
     document.getElementById("main-sideline").onclick = function() {
     alert('clicked');
     };

})();