Question: I created a new app last week with the purpose of using Facebook insights for our website, but it is not available in the list to make the connection with. Do I need to do anything to make the app selectable?

For any of you people who think this question is not technical and shouldn't be here, I was directed here from Facebook bugs because it's not a bug.

Answer: 
Not sure if this is the case here. But I **do know** that there is a threshold to see insights with regard to pages.

[As detailed here](https://developers.facebook.com/docs/insights/) in the FAQ's -

> 
> Is there a minimum number of users to see Insights for Pages? Yes. For
>  user privacy reasons, Insights are only provided to Pages with greater
>  than 30 users who like that Page.
> 
> 
> 

Perhaps there is a limit for domain insights too. You should allow some time and some traffic pass before the insights start being able to give feedback...
I had the same error, I tried to debug my site here [FB Debugger](https://developers.facebook.com/tools/debug)
which is the official debugger you can input URL, Access Token, or Open Graph Action ID.

It works for me.