I'm having some problems loading a model taken from grabcad. It is a spring  and if I try to load it with OpenCascade Import/Export example (version 6.5.2) it seems to have some problems.
Among attachments the results with Import/Export that lack something. If I load it with an app written by me using OpenCascade I have the same problem and 4 faces give me null triangulation. I have the same problem with other models, too. The model Springs.igs is the smallest that give me this problem.
What could be the problem? Any suggestions? Is there any parameter that i can set in the igs reader to resolve?
Thanks in advance.