how do I fix my key fob for toyota 5000 scorpion alarm system?

I have a spare key fob for my Toyota carina, it doesnt work,the battery is new the lights work , my husband has tried to get it in sync with the car but to no avail, I had abad experience whilst shopping dropped my car keys (with the fob what works), luckily they were handed in so I was able to get home , but hubby says after that he`d better carry his spare keys, but he has the fob that doesn`t work.Our car is a1995 Carina 1.8 GLS, is it possible to get this spare fob working?