When you define a cost activity (in the Cost Activity window), the system automatically creates a bucket of activity with the same name as the activity. Use this tab to see the activity for a selected bucket.
Optionally, you can create a bucket of activity first (in the Cost Bucket window, selecting Bucket of Activity as the cost bucket type), and then connect it to an already defined activity (by placing the cursor in the Activity ID field in the Bucket of Activity tab, and using List of Values); this would be the case if you, for example, wanted to connect the same activity to several different buckets.
The consumption of activities is what drives costs through the system. The activities themselves are not cost generating. It is their connection to cost centers that causes them to represent costs.
Set up activity costing basic data