If you mean the "Addon Manager" is telling you GSX Level 2 Expansion is not Active, it's because you haven't activated it yet, using the "Register Serial" button of the Addon Manager.
And, of course, GSX and GSX Level 2 are two separate products, each one with a separate activation and a separate Serial Number so, check they are both Active, before using any of the GSX Level 2 features.