I have a very basic Zojirushi, with just a cook and warm option. I rinse the rice, using the provided rice measuring cup, and add the water according to the markings.
Were you making brown rice? That can take a little longer to cook.

Make sure you are using the right markings on the side of the container for water level. Ours has different levels for brown rice, sushi rice, unrinsed rice, regular white, etc. Ours also has settings for type of rice so perhaps a combination of wrong water level and cooking under the wrong setting?

Apparently I am an idiot because I got a Zojirushi rice cooker, which other people I know swear by for perfect rice, and for the life of me I can't understand the directions. I liked the idea of it so that I could set the timer and have the rice be ready when I get home from work, but the first time I tried it (just normally, not using the timer) the rice was not cooked properly. Are there better directions someone can point me to online?