Not able to check the properties of a pop up window

We are testing a WPF application where in when we click on particular object, a pop window should appear. There are two buttons in pop up window where we need to click one of the button and then proceed further with other actions.

TestComplete recognizes pop window as a single object, it doesnt recognize the buttons inside the pop up window.

I am not able to do ObjectSpy on that pop window to see the properties of that buttons nor i can do checkpoint, the pop up window disappears.

Please let me know your solution for this.