Why can't I use our spare key to start the car without triggering a security feature that won't let the car start?

What is your question?

I could not find the key to our I 30 this morning, so I used the spare key. The car refused to start (battery strong, kept turning over and over), and I tried a number of things (locking and unlocking door using key, removing the fuse for the security system, waiting and then replacing it). Nothing worked. Eventually, I found the other key and the car started right up. I would like to know what is required in order to use the spare key---otherwise, why do we have it? Thank You

What makes this problem better or worse?

Using the original key

How long has your 2000 INFINITI I30 had this problem?

It has happened several times before