Found that widget with the following script interferred the plugin work:
<!–START Scripts : this is the script part you can add to the header of your theme–>
<script type=”text/javascript” src=”https://www.akhmadi-invest.com/wp-includes/js/jquery/jquery.js?ver=2.6.10″></script>
<script type=”text/javascript” src=”https://www.akhmadi-invest.com/wp-content/plugins/wysija-newsletters/js/validate/languages/jquery.validationEngine-ru.js?ver=2.6.10″></script>
<script type=”text/javascript” src=”https://www.akhmadi-invest.com/wp-content/plugins/wysija-newsletters/js/validate/jquery.validationEngine.js?ver=2.6.10″></script>
<script type=”text/javascript” src=”https://www.akhmadi-invest.com/wp-content/plugins/wysija-newsletters/js/front-subscribers.js?ver=2.6.10″></script>
<script type=”text/javascript”>
/* <![CDATA[ */
var wysijaAJAX = {“action”:”wysija_ajax”,”controller”:”subscribers”,”ajaxurl”:”https://www.akhmadi-invest.com/wp-admin/admin-ajax.php”,”loadingTrans”:”Загрузка…”};
/* ]]> */
</script><script type=”text/javascript” src=”https://www.akhmadi-invest.com/wp-content/plugins/wysija-newsletters/js/front-subscribers.js?ver=2.6.10″></script>
<!–END Scripts–>
<div class=”widget_wysija_cont html_wysija” style=”background: salmon; padding: 5px; border-radius: 9px;”>
<img src=”https://www.akhmadi-invest.com/wp-content/uploads/2014/08/news-icon.png” width=”100px” height=”100px” align=”right”/>
<div id=”msg-form-wysija-html53e88cc1c28ed-2″ class=”wysija-msg ajax”></div><form id=”form-wysija-html53e88cc1c28ed-2″ method=”post” action=”#wysija” class=”widget_wysija html_wysija”>
<div class=”wysija-msg”>
<div >
</div>
</div>
<div class=”wysija-msg ajax”>
</div>
<input type=”hidden” value=”f994767a26″ id=”wysijax” />
<p class=”wysija-paragraph”>
<label>Имя</label>
<input type=”text” name=”wysija[user][firstname]” class=”wysija-input ” title=”Имя” value=”” />
<span class=”abs-req”>
<input type=”text” name=”wysija[user][abs][firstname]” class=”wysija-input validated[abs][firstname]” value=”” />
</span>
<label>Адрес электронной почты <span class=”wysija-required”>*</span></label>
<input type=”text” name=”wysija[user][email]” class=”wysija-input validate[required,custom[email]]” title=”Адрес электронной почты” value=”” />
<span class=”abs-req”>
<input type=”text” name=”wysija[user][abs][email]” class=”wysija-input validated[abs][email]” value=”” />
</span>
</p>
<input class=”button4″ style=”width: 150px !important; margin-left: auto !important; margin-right: auto !important;” type=”submit” value=”Подписаться!” />
<input type=”hidden” name=”form_id” value=”2″ />
<input type=”hidden” name=”action” value=”save” />
<input type=”hidden” name=”controller” value=”subscribers” />
<input type=”hidden” value=”1″ name=”wysija-page” />
<input type=”hidden” name=”wysija[user_list][list_ids]” value=”3″ />
</form></div>
What exactly in this script should be fixed to not interfere with the plugin?