Are you guys using custom themes? If yes, myself have some the problem. Maybe you can have a look my sample.
step1,
Go into your feedburner account. Go to publicize. Then click on Subscription Management, make sure email is active(located at the very bottom of the screen. It should say “This service is active” normally it without you change, it will on active.
step2,
I see your wordpress using custom made themes, the code should at header.php
open your cpanel file, find header.php. sametime you back to feedburner account publicize- Subscription Management
you will see this Subscription Link Code, You can also offer email subscriptions from a link rather than a form. Just copy the following link code. Users who click it will be prompted to enter their email address in the form that appears.
Preview Subscription Link…
copy the code Ctrl C
step3,
at cpanel file edit header.php, you will see
<h1><a href="<?php echo get_option('home'); ?>/" title="<?php bloginfo('name'); ?>"><img src="<?php if ( get_option('woo_logo') <> "" ) { echo get_option('woo_logo'); } else { ?><?php bloginfo('stylesheet_directory'); ?>/images/logo.gif<?php } ?>" alt="<?php bloginfo('name'); ?>" title="<?php bloginfo('name'); ?>" /></a></h1>
<div id="rss">
<a href="<?php if ( get_option('woo_feedburner_url') <> "" ) { echo get_option('woo_feedburner_url'); } else { echo get_bloginfo_rss('rss2_url'); } ?>"><img src="<?php bloginfo('stylesheet_directory'); ?>/images/ico-rss.gif" alt="" /></a>
<ul>
<li class="hl"><a href="<?php if ( get_option('woo_feedburner_url') <> "" ) { echo get_option('woo_feedburner_url'); } else { echo get_bloginfo_rss('rss2_url'); } ?>">SUBSCRIBE TO THE RSS FEED</a></li>
<li><a href="https://www.feedburner.com/fb/a/emailverifySubmit?feedId=<?php $feedburner_id = get_option('woo_feedburner_id'); echo $feedburner_id; ?>" target="_blank">SUBSCRIBE TO THE FEED VIA E-MAIL</a></li>
</ul>
</div>[bad html removed]/rss-->
Step4,
copy the step 2 Preview Subscription Link…
copy the code Ctrl V, replace as below. Must becareful. dont miss
<a href="https://www.feedburner.com/fb/a/emailverifySubmit?feedId=<?php $feedburner_id = get_option('woo_feedburner_id'); echo $feedburner_id; ?>" target="_blank">SUBSCRIBE TO THE FEED VIA E-MAIL</a>
after done you will see like my https://petmyforum.com/ , i just done my one.