Problems with Zextra Migration Tool Core

I have a Zimbra OSE 7.1.2 installed but when I try installation ZMig the Zextra Core is not starting
Checking the logs it says that it is a mismatch between ZMig version and Zimbra.
For a reason ZMig detects my Zimbra version as 6.0.6 and not as 7.1.2
Any of you knows how to fix this?

I can be sure that theres a file somewhere in my zimbra that have previous version because of an upgrade procedure

Thanks all for your help