Hi Antonella
In your custom task, do you see any ITEM container element during runtime (in Technical Workflow Log)? Is it being Instantiated? If we do not have it, do we see the same ITEM in the standard task which you copied? How is it populated by the 'calling' workflow (must be used in a standard workflow- check the binding between the workflow and the task).
I have not worked in the EHSM module, however, from what you have explained, it seems that there is no instance of ITEM in your task which the WD is trying to read at runtime.
Regards,
Modak