Having just tried to create a 3D image from a Sketchup model downloaded from the 3D warehouse, I got the following message ...
2018.01.04_10h50m31s_001.png 17.92KB 1 downloads
Sketchup Version 8 is a 2012 version ... are you telling us that Sketchup models created within the last 5 years versions (being kind) can't be imported into Softplan?
I can open the model in Sketchup and re-save it as a Version 8 file, but is that expected behaviour?