Watch the priorities (strengths) of your walls and beams as they will automatically cut each other.
For example if your wall is stronger than the beam then it will automatically cut the beam.
Therefore if you try to do a SEO of the beam (operator) from the wall (target) there is nothing to actually SEO with (for a subtraction).
So in this case make sure the beam has a stronger priority than the wall.
Barry.
One of the forum moderators.
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