Compression issue? Module not being recognized

I have been trying to modify a module so I changed the extension vmod to zip, unzipped, made minor changes, zipped again and changed the extension to .vmod but Vassal doesn’t recognize the file as a module.

I think that the problem might be that I use the app provided by Apple (I use Mac OS) to zip the file. I tested it unzipping a module and zipping it again with no changes: Vassal doesn’t recognize it.

Am I right when I think that the app used to zip the file is behind this issue? If so, what app do you recommend?

On MacOS what tends to happen when you unzip something is that by default the contents of the zip are placed in a new folder that the OS creates of its own accord. After making your changes, it’s tempting to right-click that entire newly-created folder and zip that back up before doing your file suffix change. However, you now have the wrong item at the root level of the zip archive–VASSAL doesn’t find what it’s expecting and says it’s not a valid module.

What you need to do is go into this newly-created folder created after extracting your zip archive, multi-select the contents of this folder–which at a minimum will be a buildfile and an images folder, but may also contain any HTML/text help files, .vsav files representing predefined setups, etc–and compress those multiple selected items. Rename the resulting zip file and then you’ll have a valid module.

Thanks a lot!