Unable to find the text object that corresponds to the selected mapping item

I am working on CEF based desktop application and trying to automate it. The application contains multiple windows and i am able to access only one window while i am only able to maximize the other window but not able to access the objects of the other opened window.

Steps i am following : 
1. From the Name Mapping -> Clicked on Add Object

2. From the Map Object -> Drag the target to point to the object : Hereafter dragging the pointer to the desired object, its aliases has been suggested in the pop up like this 

From above image, i am able to highlight the selected object.

3. Now clicking on Ok from above window, an object is added to the Name Mapping 

4. Select the added object and click on highlight

Issue - 
After step 4, i am not able to access the object, it is not getting highlighted in the Object Browser. It is giving error as - 

Any suggestions for this???
Note : I am able to access the elements of the main window but not able to interact with the elements of the other opened window. I'm only able to maximize