Error when try to change a Item attributer after send notification by workflow.

Hi evebody,

After created a Item I send a request by workflow to some groups to enter specifications attributes. These groups has been receipt this workflows requisitons but when they tried to save new attributes after change it an error happening.

Following attached a document with screen of theses steps.

If somebody already passed by the same problems please tell me how correct it. 

Thanks a lot,

J. A