Adding a form input breaks form

Right now I have a form with one input and one textarea, and I am trying to add an input, however when I do it causes the form to not submit, I am submitting by hitting the enter key and not using a button. Current code:

<form method="POST">
Suggestion Subject: <input class="login-input" name="subject"><br> 
Suggestion: 
<textarea class="login-input" rows="8" name="suggestion"></textarea><br>
Username: 
<input class="login-input" type="text" name="name"><br>
Hit the Enter key to submit your suggestion
</form>

When I add the Suggestion Subject input, it can no longer be submitted. Any idea why?