Try this
1) Unlock the door to your car using the key blade
2) Insert your old key blade into the ignition and turn it to the "on" position, but do not start the car.
3) Roll down your driver's side window
4) Step out of the car and insert your new key into the driver's door lock, now turn the key to the left and hold it in that position for 10 seconds.
5) Now press the lock button on the FOB
6) Now press the unlock button on the FOB
*Spare key being your old and one in question being the new