I want to develop my website on custom theme at zenmate cms, is it possible. i'm asking before implement because i have been faced some script issues in past.

If you mean: "[i]Can I develop a custum theme for Zenphoto[/i]" then the anwer is yes.
In the showcase you can see examples of what other users created.
(http://www.zenphoto.org/showcase/)

And here is the guide about the basics:
http://zenphoto.org/news/theming-tutorial
You will need to have knowledge about web development/design though.