PHP：无法获得组合框的选定值

I'm trying to get the selected value of a combobox in php but the only result I get is "1" no matter what value is selected.

Here is my html code:

                                      <form name="form" method="POST" action="">
                                        <select class="dropdown-select"  name="dayscombo" id="dayscombo">
                                        <option value="1">7</option>
                                        <option value="2">30</option>
                                        <option value="3">90</option>
                                        <option value="4">365</option>
                                        </select>
                                      </form>

I'm trying to echo the selected value using:

$mydays=$_POST['dayscombo'];
echo "$mydays";

Thanks!

set your value equal to your text like <option value="7">7</option>

Are you using jQuery? Where is the send button? Try it:

//send.php
<form name="form" method="POST" action="posted.php">
<p>
<select class="dropdown-select"  name="dayscombo" id="dayscombo">
<option value="1">7</option>
<option value="2">30</option>
<option value="3">90</option>
<option value="4">365</option>
</select>
</p>
<p>
<button type="submit">POST</button>
</p>
</form>

//posted.php
<?php
$mydays = $_POST['dayscombo'];
echo "$mydays";
?>

Running link: http://missoesrestauradoras.com.br/send.php

Best Regards!