I have had a simular experince. A particular seller has provided me with a ''tracking number'' with the item. As I checked the tracking number numerous of times, it has not came up with anything. The same thing has been happening over and over. The seller has told me that the tracking number will only be able to updated when it arrives at local deport or what ever. As I used to work at Australia Post, with every tracking number you receive from a buyer, it is ment to say ''Austrlian Post approved paper work''. It should not state for 4 days or more ''No events currently found''. As I contacted Australia Post to discuss this matter, the Auspost officer has stated that they have not received anything or any paper work. So theres obviously theres a problem with a seller. As I checked his rating on his/hers profile, I have noticed that in his/hers feedback is quite terrible regaurding not receiving the product or taking forever for the product to arrive to its destination. 
I think ecrebay should review everyones bad history, if a seller gets to much bad feedback, they should be banned for life for selling **bleep** on ebay.