Success message not showing

Hello,
thank you for this great plugin, I got some problems with this success message after submitting a form. I do receive this, but the users don’t know whether they sent it or not..

this is my code;

<div class=”row”>

<div class=”col-md-12″>
<div class=”mb-4″>
[text text-337 id:form-name akismet:author placeholder "*Your Name"]
</div>
<div class=”mb-4″>
[email email-104 id:form-email akismet:author_email placeholder “*Email”]
</div>
<div class=”mb-4″>
[number contactnumber akismet:author placeholder “*Contact Number”]
</div>
<div class=”mb-4″>
[textarea textarea-339 class:form-control id:textarea x3 placeholder “*Enquiry”]
</div>
</div>

</div>
<button class=”btn btn-default btn-sm” type=”submit” value=”Submit”><span>Submit</span><i class=”opal-icon-arrow-right” aria-hidden=”true”></i></button>

thank you!