Process Control malfunction

[Chitra Batham]

Hi Everybody,
   I am working on a workflow in which there is a fork step which
gives rise to two  parallel branches. In one of the branches i am
using a Process Control step which is executed only after an event
occurs. This process control step cancels out the workitem which is
created by the step in the other branch, since i need to proceed only
on one branch.
Execution of the workflow is recurrent in nature. 
The probelm is when i generate a runtime version of the workflow and
execute it by triggering the appropriate event, it works fine for the
first two instances created i.e.the process control step cancels the
work item of the other branch successfully. But when the third time i
execute it the process control step doesnot logically delete workitem
of the other branch and this ultimately leads the workflow to take the
undesired path.
Please advise urgently.

Regards,
Chitra.