Update kills/deletes Calendar


I updated my NC from 13.? to 14.? and then 15.0.4.
Somewhere on the way i lost a complete calendar from one user!
I searched the database and it looks like this one calendar is completly gone!
Any hints!?

do you still have the old backup of 13?

if I remember correctly, there was a specific conversion of calendars in between one of the versions.