Check register_globals variable in your php.ini file - it should be set to on... If you can't modify your php.ini, use $_POST or $HTTP_POST_VARS (it depends on version of PHP, you use) array.
Also, it isn't good idea, to write such scripts as yours:
<?php
$fform = "a lot of html code";
if (display_form)
{
echo $fform;
}
else
{
do_something();
}
?>
The much better way to do this is:
<?php
if (display_form)
{
?>
a lot of html code
<?php
}
else
{
do_something();
}
?>