PHP - Form not submiteed on additional file upload button - php

Question

I have a following code with 5 file-upload buttons.
The 4 of them works properly, but when I insert the 5th upload button, my form is not submitted.
i.e. It redirects to the action page but isset() is not called.
HTML
<form action="g.php" method="post" enctype="multipart/form-data">
<div class="col-lg-4 ">
<div class="form-group">
<label for="InputName">Upload Photograph: </label>
<div class="input-group">
<span class="input-group-btn">
<span class="btn btn-default btn-file">
<input type="file" name="stud_photo" id="stud_photo" required>
</span>
</span>
</div>
</div>
</div>
<div class="col-lg-4">
<div class="form-group">
<label for="InputName">Upload Course Admissoin Receipt: </label>
<div class="input-group">
<span class="input-group-btn">
<span class="btn btn-default btn-file">
<input type="file" name="course_admission_receipt" id="course_admission_receipt" required>
</span>
</span>
</div>
</div>
</div>
<div class="col-lg-4 ">
<div class="form-group">
<label for="InputName">Upload Health Certificate: </label>
<div class="input-group">
<span class="input-group-btn">
<span class="btn btn-default btn-file">
<input type="file" name="health_certificate" id="health_certificate" required>
</span>
</span>
</div>
</div>
</div>
<div class="clearfix"></div>
<div class="row">
<div class="col-lg-4 col-md-push-1">
<div class="form-group">
<label for="InputName">Upload Character Certificate: </label>
<div class="input-group">
<span class="input-group-btn">
<span class="btn btn-default btn-file">
<input type="file" name="character_certificate" id="character_certificate" required />
</span>
</span>
</div>
</div>
</div>
<div class="col-lg-4 col-md-push-1">
<div class="form-group">
<label for="InputName">Upload Residence Certificate: </label>
<div class="input-group">
<span class="input-group-btn">
<span class="btn btn-default btn-file">
<input type="file" name="resident_certificate" id="resident_certificate" />
</span>
</span>
</div>
</div>
<div>
</div> <!-- row-->
<div class="center">
<input type="submit" value="Submit Form" name="register" class="btn btn-default btn-lg">
</div>
</form>
PHP
<?php
echo "Im goin in <br>";
if(isset($_POST['register'])){
echo "im here";
}
else{
echo "I am not there";
}
?>
Only when I insert the last Upload Residence certificate button, It goes into else block.

Answer 1

Just above the submit button, You have an error in html,
<div> // this div should be a closing div
</div> <!-- row-->
Something like this,
</div>
</div> <!-- row-->

Answer 2

The mistake was neither in HTML code nor in PHP.
I checked my php.ini file and there I found this line
post_max_size = 3M
I changed it to
post_max_size = 30M
This means at max 30 Mb of data can be posed using $_POST method.
Since I was uploading images (800-1000kb) each, It was exceeding the max size.
Changing the value worked.