SAP Message Q8423 - Given time collides with existing action

Diagnosis
You attempted to schedule an action with a start time identical to anaction already scheduled. Only one action may be scheduled for onetime.

System Response
The new action is not added to the schedule.

Procedure
Change the start time of the new action so that it differs at least onesecond from any existing scheduled action. Actions that use the sameresources should not be scheduled to run at the same time.