Switch to comission settings per role after a few time period not work correctly

The description told that set the time period with a Strtotime syntax. The code "if ($now - $_SESSION['affiliate_cookie_timestamp'] >= $switch_after) {" not deal $switch_after which is Strtotime syntax .

I have changed to if ($now >= strtotime($switch_after, $_SESSION['affiliate_cookie_timestamp'])) and work correctly.

thanks