F3 checks the class name as normal and then again lower case, for each path in AUTOLOAD. The behaviour was tweaked in 3.1.2 so if you're using 3.1.1 you may have issues. Code snippet below from base.php
:
is_file($file=$auto.$class.'.php') ||
is_file($file=$auto.strtolower($class).'.php') ||
is_file($file=strtolower($auto.$class).'.php'))
Your example won't work as it's neither correct case ("Gadgets/iPad.php") nor all lower case ("gadgets/ipad.php").