Youri,
Currently there’s an issue where in some places you can choose a field, if you try to choose a field from an aggregate model, you only see options for the fields on that model and not the aggregated functions / aliases like you’d expect. I believe this issue is what you’re running into, so we’ll notify you when this is solved in a future release. In the meantime, using the template could work, or you could also go into the XML of the page and change the field from the aggregate model to whichever of its aliases you would like to use.
Thanks!
