You gave very little detail here. Is very little actually posting to your stream (not many items do the activity) or is your number allowed on a page set too low?
Either way - here are two things to check.
1. Set the number of items to display on a page, and turn on (or off) paging. (higher number of items and paging set to on will give you a larger display)
2. If you just don't have enough 'actions' showing up in your stream, go to the plug in manager for CB and edit system actions. Turn on all the ones you want displayed. You can also create your own actions using auto actions etc.
