I purchased a latitude d505 with the Hitachi Travelstar Model IC25N040ATMR04-0 which started knocking so I got in touch with the seller and he shipped me a Hitachi with the model number HTS421240H9AT00 and once I put into the hard drive spot, it still says that the hard drive can't be found...any suggestions or anyone can tell me if that new model is compatible with my laptop thanks in advance