How do I kill my Sims by fire in Sims 3?!?

I keep trying to kill one of my players in sims 3 by fire, but it's not working. I locked her in a room with a fireplace, a fire didn't even start. I put her in a very small room with no doors, 20 rugs and started a fire with the stove and she didn't catch on fire! How do I kill her by fire?