The existing alerts and tasks that I created are not listed when I try to associate it to a rule. Why?

The existing alerts and tasks that I created are not listed when I try to associate it to a rule. Why?

For a workflow rule, all alerts and tasks will not be listed. Only the alerts, tasks and field updates with the same Record Type as that of the workflow rule will be listed.

For example: If the rule is for Leads, then only the field updates, tasks and alerts created for Leads will be available for association.