Key coding problems

[JesperFromNorway]

Hi! So, I kind of gave up on this keycoding a while back because nobody were able to figure out what the problem was, so I thought I'd ask around here.

I'm a certified Lexus Mechanic who've done lots of key coding before so I have all the necessary information and tools and skillset available.

After a lot of research and trial&error, the bottom line is that when you insert the key, the Security Lamp in the instrument panel is supposed to stop blinking. Just by inserting the key; you don't even have to turn on the ignition. This is a crucial part of the keycoding procedure.

But in my '99 mod IS200, the Security Lamp will not stop blinking once I insert the Master Key. What could be the reason for this? It renders me unable to program a new key, and I only have one left. I really need a reserve key. Any help will be highly appreciated, thanks!