problem with Database - Compare Schemas

My problem is when I click on the “Begin Comparison” arrow, I get the Session - New Connection window (?!) When I close the window, I have no results.

Now, I’m not exactly a newbie to this feature. I’ve been using Toad and this feature since ver. 8. I have my source & target schemas selected, and object types selected. The problem seems to have cropped up when I upgraded to 11.6.

Any suggestions would be greatly appreciated.