Thats more a problem of the ovh image then ispconfig, as jailkit has to be installed before ispconfig gets installed (see installation instructions), otherwise jailkit will not work as the jailkit install overwrites some ispconfig files. You can fix this e.g. by updating ispconfig:
http://www.faqforge.com/linux/contro...e-ispconfig-3/
and choose to reconfigure services during update to fix the broken config files.