Click on " Store using the database settings below" disables the field

Hi

I have a computed field called "expert".
Computed code:

$node_field[0]['value'] = "Drupal";

Display format:

$display = $node_field_item['value'];

When I use the field and don't click on "Store using..." the field calculates the value just fine and it shows up on the node - ie the word "Drupal"

But then when I click "Store using the database settings below (required for Views use)", which I want to do to show it in a view, obviously, the calculated value becomes "0", as displayed both in the View and on the Node itself. This is before AND after I edit and save the Node. Why the heck would this happen?