I check BMW WDS and it seem the key is before 1999. After 2000, the key are diamond shape.
But the instruction to resyn the is the same procedure. So Alex, you might still have a chance to get the new key to work.
Initialization Procedure.
1. Open central locking system using the car key.
2. Get into the car and close all doors. (Must ensure that all doors are close or it would not work)
3. Using the car key, switch the ignition lock briefly to position "1" and then switch off again. Remove the key from the Ignition. (Please do this switching within 5 seconds or otherwise the system is not ready for initialization.)
4. At the remote control key. Press the "OPEN" button (2) (->) and keep holding it.
5. When holding the "OPEN" (2) button, press the "LOCK" (1) button three time in sucession.
6. After pressing the "LOCK" (1) button 3 times, release the "OPEN" (2) button.
7. If the initialization process is successful, the door will lock and unlock immediately to confirm the process.
8. repeat Step 4 to Step 6 for second key within 5 seconds.