That means that no documents where found inside the document you are running the snippet.
Use &parents=`your list of ids`
Try this
[!Ditto? &parents=`20,30` &tpl=`detailedEvent`!]
Replace 20, 30 with the the parent(s) of the container you want to display children for.
Also make sure the documents are published and have the Show in menu checkbox selected.
Please post your code and document structure.
So what do you want to achieve? What is the output you would like.
Are the ditto calls only for Event01 and Event02?
I do not understand why are you using a depth of 2 and total 1
Why are you using Ditto display Event01 on the Event01 page?
You can simply use [*yourTV*] in the template. Ditto is for creating a list of documents.
In your Events template remove the ditto call and enter
[*pagetitle*], [*eventLocation*], [*eventDate*]