It works fine for me. I'd change the function to:
function countdown ($dateto) {
$tstampfrom = time();
$tstampto = strtotime($dateto);
$datediff = $tstampto - $tstampfrom;
$daysdiff = $datediff / 86400;
if (round($daysdiff, 0) > $daysdiff) {
$numdays = round($daysdiff, 0);
} else {
$numdays = round($daysdiff, 0) + 1;
}
return $numdays;
}
and this:
if ($countdown != "")
{echo "There are just " . $countdown . " days remaining to get your ticket!";}
to something like this:
if ($countdown < 0) {
echo 'There are just ' . $countdown . ' days remaining to get your ticket!';
} else {
echo 'Too late.';
}