Error: Check OptiStruct input file


Updated by Altair Forum User
Hi!
I received the following error message in SimLab when I tried to solve a Normal Mode problem with the solver OptiStruct:
Error: Check OptiStruct input file.
I have followed a tutorial, so I do not think there is something wrong with the boundary conditions, and when I tried the same thing a few days ago it did work. (I have tried different set ups as well, but receives the same error message).
Do you know what could be wrong/what can I do to search for the problem?