That being true ... and other DBs are truly replicated from your logging server to the Traveler server, you should be able to see the replication events in "replication history".
If all this is true (that is, you confirm another database on the same server is allowing/granting access), the attempt to access the database itself seems to be the problem.
Do you know if there are agents trying to reach the database? Or is it exclusively replication that's occurring?
More likely: if exclusively replication, we're down to, the database isn't really granting access. It'd have to be checked using an API call to be sure, but sometime y'can discover what's up by inspecting the ACL entry very carefully.
Less likely: if not, that is, if you have an agent "reaching over" to get something from the source server, OR simply an agent running on the source server, but signed by the Traveler server -- make sure the agent looks like it has the right signer name, and that the agent was signed / saved after you last refreshed the signer's certificates.
On this last situation Mark is dead right: a "reaching over" agent requires the server be trusted. The agent signer also must have enough access to do the job.