The certificate presented by the following directory service for intersite replication was rejected because the certification ...

The certificate presented by the following directory service for intersite replication was rejected because the certification authority is not trusted. 
 
directory service:
%1 
Certification authority:
%2 
 
Replication access has been denied to the directory service listed above and the certificate has been discarded. 
 
Additional Data 
Error value:
%4 %3