"Mouse over" not working on 2 overlapping objects

I have a square that changes to red color when my mouse is over it, or else it stays green. It works fine alone but if I have another object behind of it(like a circle), it stops working. Changing the “order in layer” option wont fix it also. Both objects have box collider 2d. See the images. Any helps? Thank you very much.

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Can you share your code (Using code tags please)?