There is a lot going on behind the scenes in the calculator that you don't know about. If you don't know anything about matrices, this will sound like gobbledygook.

The calculator uses matrix algebra to create regression curves.

It can only do this if your original matrix (i.e. your lists) is square and non-singular. In other words, you must have the same number of rows as columns, and there exists another matrix that can be multiplied by your original matrix to get the identity matrix. This "other matrix" is known as the inverse matrix.

In your case, your original matrix is singular, so no inverse matrix exists.