DBItem loading problem, when multiple keys are used

By default In-Portal looks for an ID of DBItem that is accessed from template in the url. When item ID is missing, but it's data needs to be displayed on a template, then "no_permission" template is shown.

As a part of customization process developer sometimes needs to load DBItem from database using not it's ID, but a combination of fields.
All works fine until nothing is loaded by a field combination.

In this case <inp2:prefix_Field name="IDField"/> tag returns "Array" field instead of "" as usual for unsuccessfully loaded DBItems.