I didn't have time to install timeline object but I will take a shot in the dark...
Is the problem that the one underneath gets selected when you click on the top one?
If this is the case then put the bottom ones on a lower layer of their own, say a "solution" layer and the problem ones on a "problem" layer. This way only the top one will be selected and you can then hide it after its clicked or whatever to reveal the solution..
A second way would be to make an invisible object where you want the solution to show and then simply spawn the solution sprite to that invisible object when its needed to be displayed...