Issue in triggering events in task

Hi,

In my workflow there is a fork and after a fork there is a task for which triggering event is defined and this particular event is triggered from zprogram and agent for task is determined using a rule.

In zprogram logic is written as event (triggering event for task) is triggered when all 4 users in fork presses submit button.

Problem is when 4th user presses submit button workitem is created in workplace of agent defined for task and in 4th user as well.Workitem should not be created for 4th user.

Please suggest.

Regards,

Kaustubh.