In my custom policy, I try to hide email_intro label but without success :

- This is my html code :

<div id="api" data-name="Unified">
    <form id="attributeVerification">
        <div id="attributeList" class="attr">
            <ul>
                ...
                <li class="TextBox">
                    <div class="attrEntry">
                        <div>
                            <div class="verificationInfoText" id="email_intro" style="display: 
                            inline;" aria-hidden="false" aria-live="polite" 
                            role="alert">Verification is necessary. Please click Send button. 
                            </div>
                        ...
                        </div>
                    </div>      
                </li>
                ...                             
            </ul>
        </div>
        <div class="buttons">
            ...         
        </div>
    </form>
</div>

- My JS code

var intro = document.getElementById("email_intro");
intro.style.setProperty('display','none');

Could someone know what the error might be please?

PS : I do the same thing to other elements and it works!!