Boy Lines Up 3 Cups For His Magic Trick, But There’s Just One BIG Problem! Can You See It?

This boy wanted to impress his sister with a magic trick.  He had it all figured out.  He had three cups lined up and there would be no way that she could guess which one held the blue bottle cap.

She closed her eyes and he moved the cups around to further distract her and make it even harder to tell which cup it was under.  But it seems that the boy forgot just one major thing.

What’s wrong with this trick?