the following sequence of steps is described to form an opening:

1)The lines are entered by using tools for input of joints and lines

2)The macroelement without opening is defined using the macroelement input tools.

3)The openings are entered by choosing the tool for opening and selecting all lines forming
each opening.

when Ii tried that, I had this message: " A macro-element with identical topology already exists."

what have I done wrong?