2013-08-14 06:56 AM - edited 2013-08-14 07:03 AM
2013-08-14 09:18 AM - edited 2013-08-14 09:19 AM
Make sure Homer is in Krustyland, he starts the 15th quest and the exclamation mark is only shown if hes there and has nothing to do.
If you want to know whos starting which part of the quest: