Check the following:
Do you have another card in the field? Also make sure NFC is off in your phone when using the grabba. Your card could also contain dual technologies (mifare + iclass). To get the raw data, enable the HID Return raw data option, that will give you most information about the card.
Key refers to an encryption key. The encryption key is never read. If your card has custom encryption keys, you will need to load them using the Type hex key to load.
Try using the default keys first.