Listings not appearing in search

[triode300]

Both myself and friends have noticed that a lot of items are not being returned - even when an exact search is performed of the item's title. There are no restrictions placed on the search. A hypothectical example would be an item with title "Sony ABC123 CD player black with wood sides". A search for "Sony ABC123" does not return the item and even searching for "Sony ABC123 CD player black with wood sides" does not return the item. I have found ebay links to items on other websites which take me to an item of interest. However, if I search directly it does not appear - even though similar items are returned. A friend has contacted ebay previously with specific  examples, but no response has ever been provided. We are finding this is happening a lot, but of course if items are not being returned in searches, one will never know.