SAP Message XS843 - No delivery to & since errors occurred during encryption or signature

Diagnosis
The message was not delivered to the recipient &V1& because it couldcould not be encrypted or signed by the security proxy. A missingcertificate could be the cause of the problem.

System Response
Processing was completed.
Additional information about the node (if available, in system languageof node):
V4

Procedure
Check the settings of the security proxy.