Cut under angle problem

[Anonymous]

Hello,

I was using Structural elements/openings for the needs of perpendicular to main axis openings in slabs. However I cannot use that tool when it comes to the cut under some angle. I was trying to use Polyline - Contour or Rectangle by three points, but I never get opening in the panel.

Any thoughts what I am doing wrong?

For better understanding please see attached print screens.

BR 

[Artur.Kosakowski]

What about replacing a slab with two smaller panels?

If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.

[Anonymous]

Finally I managed to prepare cut, somehow. It's strange how capricious Robot is. Nonetheless thank you for help.