I remember having the problem awhile ago but i cannot find the solution again using Google etc. So i thought i'd post on here.
I'm trying to add a module so that it can be selected in the instance creation wizard. I can select from many other modules including WFFM.
But i cannot see Sitecore Experience Automation (SXA) when i place it in the repository directory or select it to be added during the process which prompts "Selected file is not a sitecore module package".
The package contents look correct but i cannot remember what typically breaks these packages for SIM. I'm sure it was something simple :)