problem creating android project on netbeans

According to the documentation:

  

To avoid conflicts with other developers, you should use Internet domain ownership on the basis of your package names (in reverse). For example, applications published by Google start with com.google. You should also never use the com.example namespace when publishing your applications.
  The package name serves as a unique identifier for the application. It is also the default name for the application process (see the element process process attribute) and the default task affinity of an activity (see the element's taskAffinity attribute).

The package name serves as the unique identifier for the application, and to avoid conflicts you must use the internet domain of the inverted application owner, for example, Google applications start with com.google . For test level you can use the package name com.testes which would be the opposite of an assumed http://testes.com .

Probably there is some verification that is based on the fact that no domain has only one part, so the IDE tests if its package has at least two parts, if it does not have it, it does not allow you to go forward.

Reference: Android Developers