Hello Daniele,
I've seens similar issue before when a 'brief consultant' was assigned.
The problem was caused by assigning a health surveillance protocol with protocol category 'CONS', brief consultation. This should not be possible because brief consultations are not planned.
The following note corrected this behavior
1690471 - Brief consultations in the planning cockpit are not allowed
For resolving the problem with the error messages for persons which has a brief consultation assigned in the planning cockpit, you may have to delete the entries in table T7EHS00_PERPROSC with protocoll category 003 (CONS).
Hoe your issue is similar 
Kind regards,
Raphael