Queries shouln't contain unmanaged devices. There is no data to query on them in the DB. Potentailly there is another managed device that has the same IP/Hostname/MAC (even if it is an old device and an old IP or something) that is still in the DB messing things up. Try using the following doc to search the DB for the MAC or IP of the Unamanged device.
http://community.landesk.com/support/docs/DOC-2901
MAC address should use no - or :
IP follows 010.000.000.000 format.