problems with array_search()

[Antivirus]

Ok this is driving me nuts... all common sense tells me this should work however it does not.

PHP Code:

$oldname = 'Tiger';
$newname = 'TigerXXX';

$options = array(
    [0] => 'Cat'
    [1] => 'Cow'
    [2] => 'Monkey'
    [3] => 'Snake'
    [4] => 'Tiger'
    [5] => 'Zebra'
);

if($key = array_search($oldname, $options))
{
    $options[$key] = trim(unhtmlspecialchars($newname));
    asort($options);
} 


By all accounts, 'Tiger' should be replaced with 'TigerXXX'... shouldn't it? This is what I am expecting but it's not working out. Seems that array_search() is returning false.

Anyone know why?