To be sure that everything is perfect with your app package, let Visual Studio do everything.
Right click on your project -> Store -> Create App Packages... -> Next -> Sign in to your dev account -> select reserved name (if there is already published package in the store, select the box which enables you to see the name of apps with published packages) -> And do the rest...My advice is to check with Visual Studio if your package will pass to store (you will see that button), and if yes, publish that package.