Hey, I think I may know what the problem is.

The "zip.exe" tool you linked to is actually working the way it's intended. It doesn't have a GUI (graphical user interface) like other programs you're used to, because it's actually meant to be run manually by entering commands in Command Prompt or batch scripts. I could probably figure out the proper commands you would need to run to properly compress an EPUB with that tool, but it's fairly complex and time-consuming, so it may not be what you're looking for.

I looked around and managed to find another open-source tool called ePubPack (which has a GUI) that might do the trick. I also tested it on my Windows 8.1 machine, so compatibility shouldn't be any issue.

Once it's installed, and you have your ebook file/folder structure ready for compression, just open the tool and select your "mimetype" file, and choose the filename/location for your EPUB file. As long as you've got your files structured correctly for the EPUB format, it should work without any errors.

Let me know if this works for you!

~ (^{A V}_T^O_A^H_M^K_E^A_R^H)

Okay, thanks. I'll try it out later and update this comment with my results.

Edit:

Once it's installed, and you have your ebook file/folder structure ready for compression, just open the tool and select your "mimetype" file, and choose the filename/location for your EPUB file. As long as you've got your files structured correctly for the EPUB format, it should work without any errors.

I downloaded the program you linked to with no trouble. Also, it does open and stays open, too, which is great.

But for some reason I cannot select my mimetype file, even though I am fairly sure I have constructed all the files correctly. I could be wrong, though, so if you have any ideas I'd be willing to try 'em.

-TNTOS-

I'm definitely able to use this tool to recompile other existing EPUBs I've decompressed manually, so the issue very well might just be your folder structure or perhaps a file that's formatted incorrectly or missing.

I wouldn't be able to tell for sure unless you can provide me with a screenshot, file structure list, or download of your folder structure to look over and see if I can find the problem.

I'm definitely able to use this tool to recompile other existing EPUBs I've decompressed manually, so the issue very well might just be your folder structure or perhaps a file that's formatted incorrectly or missing.

 

I wouldn't be able to tell for sure unless you can provide me with a screenshot, file structure list, or download of your folder structure to look over and see if I can find the problem.

Here's a screenshot of the file structure list.

-TNTOS-

I'd try removing the ".txt" extension from your mimetype file's filename (so that it's just simply "mimetype").

By default, that file has no extension, so that might be throwing off the compressor tool.

I'd try removing the ".txt" extension from your mimetype file's filename (so that it's just simply "mimetype").

By default, that file has no extension, so that might be throwing off the compressor tool.

Just removed the ".txt." extension and ePubPack decided to work. Guess that must have been the problem.

Thanks for your help . Really appreciated it.

-TNTOS-