Error in Plans (Successor)

Hi All,

I am noticed something strange with rtc 4.0

*Open a formal project and create a phase plan

*Plan view > Workbreakdown & Schedule view

* Create work items as follows ( Parent Task with 3 child tasks) and add successor links. Then close tasks one after another. So you will see a plan something like this below.

However I see errors in the plan

X : Successor workitem was closed before predecessor workitem.

I am not sure why this error comes though the resolution dates of the workitems are in correct order only.

          Please let me know what is the reason for this error.

Thanks in advance!