You have a problem with your theme. Since it is not one of the distributed ones, there is not much we can do to help you other than say that there is no such variable `$conf` that the theme seems to want to use.
Most likely this is a theme which was poorly constructed in the first place and has not been updated to run with the version of Zenphoto you are using.
killerbee is also an older unsupported theme as well. You should swap your theme to one of the themes included in the zenphoto distribution to check if you still have the error. Chose one of the themes that have the "Officially Supported" icon.
Comments
Most likely this is a theme which was poorly constructed in the first place and has not been updated to run with the version of Zenphoto you are using.
check out hte screenshot
http://i49.tinypic.com/atvuh.jpg