Tiki 6.7 is the LTS release, is there any particular reason you need to run this version?
the current release is Tiki 8.4
(Tiki 9.0 has been released, but it's the Beta release)
any fixes that have been made are most likely already available in the newer releases.
the actual problem may not be in maketoc, it could be to do with your SEO link,
have you checked that this is setup correctly?