connecting slack to botman in laravel on localhost

This is my routes file in laravel. Am matching any url with /botman that calls a closure which, registers a slack driver for botman and listens to the message hello.
In slack am trying to set the Request URL under event subscriptions using this http://127.0.0.1:8000/botman. I get "Your URL didn't respond with the value of the challenge parameter.". What am I missing? is it on my routes file? or the url?