Mail form problem, Radio button not working Options

[ApoMarn]

Can anyone tell me what I'm doing wrong here?

$email_message = .......
$email_message = "Medium: ".$medium."\r\n";
$email_message = .....

<FORM action="inspection_copies.php" method="post">
...
<p><input type="radio" name="medium" value="CD-ROM" checked> CD-ROM
<br><input type="radio" name="medium" value="USB drive"> USB drive
...
</FORM></b>

The rest of the form works perfectly but the radio button line sends only the title (Medium) without any value.