show Next/Previous button

<?php
$next_group_id=custom_get_next_group_id();
$prev_group_id=custom_get_prev_group_id();?>
<?php if($prev_group_id):?>
<a href="<?php echo custom_get_group_edit_link($prev_group_id) ;?>" class="alignleft">Previous </a>
<?php endif;?>

<?php if($next_group_id):?>
<a href="<?php echo custom_get_group_edit_link($next_group_id) ;?>" class="alignleft">Next </a>
<?php endif;?>