type AsFacetRange requires missing column [uniqueIdx]

I am trying to implement the product cockpit on our upgrade project from 6.4 to 2105.

In doing so, running the required .impex files I am getting the following error

target type AsFacetRange is not permitted by current header - type AsFacetRange requires missing column [uniqueIdx]

Any idea as to why this happened?

Is there a true guide as to what are the steps needed to implement the product cockpit correctly on an upgrade/update type of project