The exception that is shown on screen is probably already routed thru the errorController. Go in your views folder there should be a error folder with the view script for errors. Go in there if you want to style them.
Ok so you ar enot seeing anything after enabling the errorController from zedntool.
Looking at your folders is the a ErrorController.php in your Apllication/Controllers directory?
Is the a error folders in you views folder with a index.phtml file in it?
Looking at your application.ini file. Are these lines properly set?
phpSettings.display_startup_errors = 1
phpSettings.display_errors = 1
How you know it doesnt work?