Error message when clicking Calendar "view item" button

Greetings,

I've just upgraded ES on a site that is in development . Yesterday, I upgraded from 1.1.6 to 1.2.6. Today I went to 1.2.7. I'm running on Joomla 2.5.19.

When I click on a Calendar item in the Stream I get a detail view page with the ability to comment on the Calendar item. (.png attached)

When I go into the Calendar app and click on the item, I get a popup that includes a View Item button.

Prior to the 1.2.6 upgrade, per my client, clicking that View Item button took him to the same view as in the picture.

Now when we click the View item button we get an error message.... "Sorry, but you cannot access this page because the user did not install the application"

Thanks for your help.

Dave