change extension?

[verybadcat]

I want to change the extension of one of my files from .zip to .epub. Yes, it is a zip file. I know I want to do this. But the OS won't let me! Any time I change it to .epub, it either changes it back to .zip, or changes it to .epub.zip, which is also no good.

This is under snow leopard.

I have resorted to transferring the file to a PC, changing it there, then transferring it back. But there must be a direct way to do this in OSX. How?

 

[DeltaMac]

Go to your Finder Preferences, then the Advanced tab.
Is "Show all filename extensions" checked?
You can also uncheck "show warning before changing an extension" if you feel good about that!
with that 'show all extensions' un-checked, the .zip remains in a hidden state (whether or not you can actually see it - weird, eh?), and may ignore the fact that you want to select it and change to something else.
Just so you know, I did verify what you are seeing, and also checked the fix. It should then allow you to change the extension completely. Hopefully, the result for you will be what you intend to happen.