PHP compare time variables with if/else

I am trying to echo some text depending on the results of a timestamp, using an if/else statement.

My logic is as follows;

Based on the value of $data;

• If no results => echo 'no results'
• If date is less than todays date => echo 'expired'
• Else => echo 'active'

The problem I am facing is that currently my code always displays 'active' no matter what the date is - my code so far is;

<?php

$data = get_patronapi_data($id);

$dataTimestamp = strtotime($data);
$now = strtotime('today');

//echo strtotime('now'); this outputs 1446820684 
//echo $dataTimestamp; this outputs 1954886400
//echo $data; this outputs 31-12-13

//if $data is empty
if (empty($data)){ 
  echo 'no results';
}
   //if $data is not empty but date is less than today
   elseif (!empty($data) && $dataTimestamp < $now) {
    echo 'expired';
   }
     //everything else
     else {
      echo 'active';
     }
?>

I'm sure the answer will be obvious to a pro but you have a newbie here!