Cause

Either

(a) you have attempted to combine some shapes (see Combine Shapes) that do not intersect,

or (b) you have subtracted shapes so that no shape will result.

What Can I Do?

image\BULLET.gif Move the shapes so that they intersect.

image\BULLET.gif Change one of the shapes to be different from the others.

If you have tried to slice using a line, ensure both ends of the line are outside the objects being sliced.