Based on the startup prcess of the IA does any of this help.

1. First it reads the oratab file to see what services are on the host
a. Is the oratab file in a default location?
b. Is it readable by the agent user?
c. Are the services listed there?

2. Once the oratab file is read it reads the listener.ora from the $ORACLE_HOME specified in the oratab file.
a. Is the listener.ora file in the default location?
b. Is a GLOBAL_DBNAME defined if not it reads tnsnames.ora

This will create the services.ora file, as you do not have any entries in this file looks like there is a mistake in the definition of one of these files.
oratab
listener.ora
tnsnames.ora

Can you review them and check they are okay, if you still cannot resolve the problem post the contents and give the locations back on this thread

Regards