Stair case created in Sketchup don’t pierce a hole through the floor and I can’t see down the stairs

[titust11]

I couldn’t find an L shaped stair case in the library, so I created it in Sketchup, exported it in Collada format, then imported it is SH3D. Although the dimensions of the stair case are good it does not make a rectangular hole in the floor/ceiling. On upper level it just shows the highest step, but I can’t see down the stairs. What should I do?
1. Maybe i need to do some changes to the Sketchup model in order to pierce the floor, but don’t know what exactly.
2. Maybe someone can tell where to find a SH3D native model shaped in L
(10 steps down, small square platform and 4 steps to the right)

[hansmex]

When importing your staircase, check Stairs in step 2

H