You want to zip from the folder (not above it). And you want to be sure nothing else is in the ZIP other than the zimlet files. If you are making your zip on Mac (and using the UI "Compress" feature), it will put other hidden Mac stuff (__MACOX stuff) in there which will cause the zimlet t...

The name of your zimlet, the folder and the zimlet definition file name xml all need to match. Looks like you have a zimlet named "root_domain" but have your zimlet definition file named ="root_domain_SIS.xml".Here is what your zimlet folder structure should look like (for exampl...

What kind of Zimbra development do you plan on doing?
- UI (Branding/Skins/Themes)

- Zimlets

- Other
There are some tips/tricks on doing Zimbra development on this wiki page. It talks about how you can use Zimbra Desktop to create a zimlet dev environment quickly:
ZimletDevSetup - Zimbra :: Wiki