undefined index from form post (untypical) - php

Question

Here is the page with a table, which contains info rows that generates for every row from request.
<table class="table table-hover">
<thead>
<tr>
<th>ID</th>
<th>Account</th>
<th>Level</th>
<th class="text-center">Action</th>
</tr>
</thead>
<tbody>
<?php
$mysqli=connect();
$result=$mysqli->query("request is here");
while($rows=$result->fetch_assoc()) {
echo "<form action='script.php' method='post'>";
if ($rows['admin']>$_SESSION['admin']||$_SESSION['admin']<6||$rows['online']==1)
$levelinput='<td><input type="text" class="input-sm
form-control" value="'.$rows['admin'].'" disabled></td>
<td class="text-center"><input type="submit" class="btn btn-
simple btn-sm" value="Change" disabled></td>';
else $levelinput='<td><input type="number" class="input-sm
form-control" name="level" value="'.$rows['admin'].'"></td> ----- LEVEL IS HERE
<td class="text-center"><input type="submit" class="btn btn-round
btn-simple btn-sm btn-warning" value="Change"></td>';
if ($rows['ucp_online']>time()-60*5) $name=$rows['login']." <span
class='label label-success'>ONLINE</span>";
else $name=$rows['login'];
echo '
<tr>
<td>'.$rows['id'].'</td>
<td><a href="/admin/user.php?id='.$rows['id'].'" class="btn
btn-simple btn-sm">'.$name.'</a></td>
'.$levelinput.'
</tr>
<input type="hidden" name="admin" value="'.$rows['id'].'">
</form>';
}
$mysqli->close();
?>
</tbody>
</table>
Form moves us to script.php, which takes only $_POST['admin'] index and don't takes $_POST['level'] index. And of course, at the page level value displays correctly.