Oracle Database Discussions

Hi!
I'm trying to configure EM database control. I've tried both dbca and emca without luck.

When running dbca I only get the "create database" and "manage template" options. What I want to run is "Configure Database Options". I've sat the ORACLE_HOME/ORACLE_SID environment variables before starting dbca. Why does not DBCA recognize that there is already installed one database. Could it be a issue with my oraInventory? What should I be looking for if so?
I should also mention that I can logon with sqlplus with my current settings.

An indication that there are problems with oraInventory is that when running emca I get the following error:
"Database instance unavailable"

Where can I find the log files from emca?

Thanks
/Heyers