First – Let me explain, How to set any new theme as default theme.
e.g The directory structure for magento templates and layout is “app/design/frontend/” then there is package name “default” or “blank” or “anything you have as package ”
You can set this package from admin panel
System -> Configuration -> Design -> Package.
(In magento there is “default” so leave it as it is if your package is “default”)
Now in our product we provide theme for default package so you do not have to change package, you just have to set theme.