The PTBurn Client is not seeing the Server -or- The Server can't see the Client.
Client finding Server. In order for the Client to "see" the Server you must be able to browse to the Server computer through My Network Places, open the PTBurnJobs folder, write a file to that folder and delete a file from that folder. This must be accomplished without being prompted for or entering a password.
Domains and Subnets. If the above can be accomplished from a client in another domain and on another subnet, you will not have a problem.
Server finding Client. The Server should detect all clients on the same Microsoft Windows Network as itself. Go to My Network Places - Choose "Entire Network" - Find the network that contains the Server Computer attached to the Disc Publisher, click on it to open it. All other computers shown in this network will be detected by the Server Computer.