If you are prompted to Convert to File Geodatabase(from a Personal Geodatabase) when you first open an analysis, select Yes.
-OR-
From the Scenario 360 toolbar drop-down menu, choose Analysis and then select Convert to File Geodatabase.
Once you convert to File Geodatabase A type of geodatabase used by ArcGIS in versions after 9.1 and in Scenario 360 in versions after 3.2., you may not convert back. For more information, see About Geodatabases.