Based on what the tracking number is giving you, I'm assuming the item is coming from the States, correct? More than likely, the "tracking number" you have been given is a Proof of Shipment number which proves that the seller has shipped the item. Even when you do get the item, the "tracking" information will probably still not change.
How long has it been since the seller shipped it? Items from the States can take around 2-4 weeks, most likely the latter since it is Christmas time. Keep in mind all Paypal claims have to be made within 45 days.