php - set_exception_handler not working -

i'm working on small site has custom error handling (or, rather error visualization) , i'm having issue function involves both error , exception catching.

so, have code:

<?  $query = sql::query("select * sitevars");  if ( !$query ) {     kernel::log('could not retrieve sitevars.', 3, true);     return false; } 

as can see, supposed use kernel::log method if query false kernel::log block takes care of launching exception if third argument equal true written follows:

<?  if ( $kill ) {     $backtrace = debug_backtrace();     $caller = array_shift($backtrace);      echo "test";      throw new exception($message." near line ".$caller['line']." on file ".$caller['file']); } 

now, issue that, though test printed, exception handler not called. set exception handler on __construct method of kernel class

<?  public function __construct() {     global $config;      self::$modlist = array('kernel');      spl_autoload_register('kernel::loadmodule');     register_shutdown_function('kernel::shutdown');      set_exception_handler('kernel::exception');          set_error_handler('kernel::error', e_all); } 

now, i've triggered errors on other files, know @ least error handler working, but, though i've executed throw new exception('test') on various files, none of exceptions caught.

why happening?