Decision Task Error

[Daniele Cattaneo]

Hi all!
Something strange happend yesterday on customer production system: user executed a decision task (copy of standard decision task) but the workflow didn't get the answer so the system doesn't know how to proceed.
>From the workflow log I can understand that: the workflow is still in process, every step from the beginning to the decision step is complete, the risult of decision task is empty. It seems that the workflow doesn't know how to preceed as there is no decision answer.
How can I solve the problem? Every transaction for workflow analysis and troubleshooting I tried had no success. Could I process this istance again (it is a posting invoice!)? Anyway, I'm worried even about the prevention of this kind of error (I never had before!!!).
Best Regards, Daniele