No RDB discovered by RZ Agent

in a newly installed environment, the RZ agent complete initialization but does not discover any RDB subnode.
The Agent Event view shows message:
“Make sure the Oracle home directory or Oracle Instant client installation directory is configured.”

The Oracle home is correctly configured into the agent instance cfg file.
I think that the problem depends on this error message I found in the log:

kdycfgp.cpp,145,”ConfigParser::parseConfig”) could not find config file: /opt/IBM/ITM/config/oraclehost1_rz_TEST1.cfg
configfile.cpp,147,”ConfigFile::parseConfig”) Error reading agent configuration file: rz

The real name for the cfg file is actually: /opt/IBM/ITM/config/oraclehost1-NAD1_rz_TEST1.cfg

And this is also the name used for all the other conf and log files used by the agent.
Why does it occur and how I can fix it ?

Thanks in advance