Clearcase problem?

Hi

I have problem making 'checkin' 'checkout'. These commands exist
in Clearcase menubar, but are not activated??? I have a clearcase
file in the buffer. 

What do I have to do exactly? How do I install the package, 
what is needed? Could you send me an example of a settings file.
I have read all there is to read, reinstalled a coulple of times.

Thanks, Hasan