Oracle internals, debugging and undocumented features
Oracle is always changing.It never ends..
The other day I was trying to install new OEM agent version 22.214.171.124.
And of course, like in the past I just started ./runInstaller command .
That did not work and I decided to dig into some documentation ( what I should have done before ) and found it is not possible to install the agent by simply invoking the installer.
They are various supported methods of agent installation.
The following link describes different methods for installing 11g agent:
They are 9 chapters describing different methods.Pick one that works for you.