Add a new custom signup button

I’m trying to add an new signup button that will open the signup modal but it doesn’t work

here is my code:

api.createWidget("custom-signup-button", {
    tagName: "button.become-member-button", function(helper){
      return  helper.attach("button", {
        label: "sign_up",
        className: "btn-primary btn-small sign-up-button",
        action: "showCreateAccount",

and this is the html code for the button:

<script type="text/x-handlebars" data-template-name="/connectors/above-footer/hp-above-footer-become-member-banner">
  <div class="become-member-conatiner">
    <div class="become-member-section">
      <div class="become-member-content">
          <div class="become-member-subtitle">{{theme-setting 'become_member_subtitle'}}</div>
          <button class="become-member-button">
            <img class="become-member-button-arrow" />
            <div class="become-member-button-text">Sign up</div>

what am i missing?