Switch not going to last case

On my page I can see who's online and away. How every it does not switch to offline.

Does not go to the last switch case seems to stop at away How can I make sure switches offline correct.

I have set it up in short time intervals for testing 

PHP Code:

$questions_userinfo = $this->question_model->get_user($question_info['question_user_id']);

$whosonlinetime = time();

$online = '';

switch ($whosonlinetime) {

case $whosonlinetime < $questions_userinfo['online'] + 300:

$online = '<span class="text-success">[ONLINE]</span>';

break;

case $whosonlinetime > $questions_userinfo['online'] + 400:

$online = '<span class="text-warning">[AWAY]</span>';

break;

case $whosonlinetime > $questions_userinfo['online'] + 600:

$online = '<span class="text-danger">[OFFLINE]</span>';

break; 
}

$data['online'] = $online; 


There's only one rule - please don't tell anyone to go and read the manual.  Sometimes the manual just SUCKS!