Modal issue autoclose

I have an issue with the modal success style, when I click the button to toggle it, it auto close it at the same time.

Here's a sample of the code I used :

<button type="submit" name="submit" class="btn btn-outline-primary" data-toggle="modal" data-target="#registerSuccess">Send</button>

 <!-- Central Modal Medium Success -->
<div class="modal fade" id="registerSuccess" tabindex="-1" role="dialog" aria-labelledby="myModalLabel" aria-hidden="true">
<div class="modal-dialog modal-notify modal-success" role="document">
<!--Content-->
<div class="modal-content">
<!--Header-->
<div class="modal-header">
<p class="heading lead">Congratulations</p>
<button type="button" class="close" data-dismiss="modal" aria-label="Close">
<span aria-hidden="true" class="white-text">&times;</span>
</button>
</div>
<!--Body-->
<div class="modal-body">
<div class="text-center">
<i class="fas fa-check fa-4x mb-3 animated rotateIn"></i>

</div>
</div>
<!--Footer-->
<div class="modal-footer justify-content-center">
<a type="button" class="btn btn-success">OK<i class="fa fa-diamond ml-1 text-white"></i></a>
</div>
</div>
<!--/.Content-->
</div>
</div>
<!-- Central Modal Medium Success-->