Is not an enclosing class Java

I’m trying to make a Tetris game and I’m getting the compiler error

Shape is not an enclosing class

when I try to create an object

public class Test {
    public static void main(String[] args) {
        Shape s = new Shapes.ZShape();
    }
}

I’m using inner classes for each shape. Here’s part of my code

public class Shapes {
    class AShape {
    }
    class ZShape {
    }
}

What am I doing wrong ?