I've tried to create a new COS, both in the web interface and the CLI and I got the following error:

zimbra invalid request: specified zimbraMailHostPool does not correspond to a valid server:
I have two Zimbra 7.1.1 running on CentOS 5.6 x86_64 serving one domain.

I guess that somehow I screwed the value of zimbraMailHostPool, becuase the id that appears in the error message doesn't correspond with the id of any of the servers. The only place where that id appears is in cn=config,cn=zimbra zimbraVersionCheckServer property. I tried changing this property to the value of any of the servers, but I got this error

ERROR: account.INVALID_ATTR_VALUE (zimbraMailHostPool must be a valid id)
Any ideas?
Thanks in advance.