Views sorting on "expires in [time until expires]" throws error

Not critical IMO because I worked around it by simply sorting my Views on "expire date" (vs "time until expires"), but just FYI. Tried setting "ed_classified: Ad Expiration delta from current time" to default sort, descending, received following error:

user warning: Unknown column 'edi_classified_nodes_expires_on_delta' in 'order clause' query: SELECT DISTINCT(node.nid), node.title AS node_title, node.changed AS node_changed, node_data_field_price.field_price_value AS node_data_field_price_field_price_value, node_counter.daycount AS node_counter_daycount, edi_classified_nodes.expires_on AS edi_classified_nodes_expires_on, users.uid AS users_uid, users.name AS users_name, profile_handle.value AS profile_handle_value FROM node node LEFT JOIN content_type_ed_classified node_data_field_price ON node.vid = node_data_field_price.vid LEFT JOIN node_counter node_counter ON node.nid = node_counter.nid LEFT JOIN edi_classified_nodes edi_classified_nodes ON node.nid = edi_classified_nodes.nid INNER JOIN users users ON node.uid = users.uid LEFT JOIN profile_values profile_handle ON users.uid = profile_handle.uid AND profile_handle.fid = '3' WHERE (node.status = '1') AND (node.type IN ('ed_classified')) GROUP BY node.nid ORDER BY in /.../includes/database.mysql.inc on line 172.