The data is saved but it looks like the edit in StandardController is used and this warning is given:

2012-02-15 21:31:36 Warning: Warning (2): Missing argument 1 for StandardController::edit() in [/Applications/MAMP/htdocs/gears/trunk/app/Controller/StandardController.php, line 264]
Trace:
StandardController::edit() - APP/Controller/StandardController.php, line 264
ReflectionMethod::invokeArgs() - [internal], line ??
Controller::invokeAction() - CORE/Cake/Controller/Controller.php, line 473
Dispatcher::_invoke() - CORE/Cake/Routing/Dispatcher.php, line 104
Dispatcher::dispatch() - CORE/Cake/Routing/Dispatcher.php, line 86
[main] - APP/webroot/index.php, line 96

There is also the error message 'CO Person "" Not Found' displayed in the browser.