Help with Mifare Classic. RPi2, PN532 NFC, Libnfc and mfoc

Hi everyone,

Ive been spending the last few days working on cloning a RFID tag, I was totally new to linux, but with some help, worked my way through adding the NFC reader and installing libnfc and mfoc.

Now ive managed to find the access key through a nested attack, and dumped this data to an .mfd file. (see below)

I have taken this, and written it to a Mifare magic card (where you can change the uid of the card).

I have changed the UID of the card to match the existing one. So the wtitten card looks like below.

The only part of the card that is different, is in Block 0, Sector 0, the manufactures block.

When i place the written card to the machine, its coming back with RFID tag error, yet the orignal tag works. Can anyone see whats happening with this and can give me some pointers?