** Problems retrieving data from Forms

Hi, I have problems retrieving data from php forms. I have no idea how to manage that problem. For example tih code is not working with me. The ID variable is never initialised.
<?
$IDD="So print function is working";
print("$IDD");
print("<br>");
print("$ID");
print("<br>");
print("
<form action="$PHP_SELF" method="post">
<input type="text" name="ID" value="$ID">
<input type="submit" value="send">
</form>
");
?>

Try doing a:



depending on your PHP version, one of those should work....