Hi Mostafa,
good that you checked that it has nothing to do with the Geometry / Solving etc.
But it can be still an issue related to infrastructure e.g. a too long paths (Workbench can handle per default a certain number of characters, with Maxwell in Workbench that is driven by optiSLang paths get very long), missing licence, missing files in the process when optiSLang runs Workbench etc.
So the mentioned/described approach above is still valid. So, the steps above are what I would check/do next.
Markus
You are navigating away from the AIS Discovery experience