Every Feed overview box, has an dual state button on the bottom right corner. The two possible states are:

Feed Status	Button status	Description
On: (Feed is checked for updates)		The feed is actively checked for updates, based on the specified Scheduling Options Stories are published on your wall according to the options (General & Transformation) specified on the Feed Editor Page.
Off: (Feed is not checked for updates)		checks are paused, and items from that feed are NOT published on your wall.

When you enable a feed that has been previously disabled, please remember to change the "Cut off Date" on your Scheduling Options. By default this date is pushed forward to the Date/Time you enabled the feed, to avoid flooding your wall with old / outdated information, but you can override that and change the "Cut off date" to suit your needs.