Hi 

Can someone explain with an example how I can use a custom attribute as key in the recommendation criteria. The documentation for making a custom attribute a key in a crieria says that

"Recommendation is determined by an item that is stored in a visitor's profile, using either user.<x> or profile.<x>attributes.

When this option is selected, the entity.id value must be present in the profile attribute"

1. It would be great to have an sample example.
2. When I try to save a criteria with a custom attribute key using logic of item with similar attribute, I get the error has invalid fields. Something that I am missing? 

Thanks

Manpreet