Typically this indicates a problem in tnsnames.ora or sqlnet.ora. Check the entry for Oracle Reports Services in tnsnames.ora. A typical entry should look something like the following:

repserver.world = (ADDRESS=(PROTOCOL=tcp) (HOST=144.25.87.182)(PORT=1951))

In this example .world is appended to the name because it is the domain specified in the sqlnet.ora file. If the NAMES.DEFAULT_DOMAIN setting is not defined in the sqlnet.ora, then omit .world from the name of the server instance.

If your tnsnames.ora file appears to be correct, then check your sqlnet.ora file. Good default settings to use in this file are:

TRACE_LEVEL_CLIENT=OFF names.directory_path = (TNSNAMES) names.default_domain = world name.default_zone = world

If your protocol is TCP, then ensure the Net8 TCP/IP adapter and Net8 have been installed. Lastly, be sure that your installed version of Net8 is not older than the version that came with Oracle Reports Services.