If you are using the box mix as the post last state it could be an old box. If not the time your taking to put it in the oven could be too long or you are not getting enough air in the mix. The cake is like an experiment and has to have the right amounts of everything and temp. in order to make it rise. Also if after the liquid goes in have everything ready to go so you can pour in the batter and put it in the oven. (The pan greased, the preheating etc.) My daughter use to forget something and go to the store and come back and did not understand why it would not turn out. the cake were like playdough bars sometimes. The bread is also tricky if the yeast is not allowed to eat the sugar and not dissolved well. The date on that is needed to be check also. If you have a stove after 1980s you might have a hot spot that can't be calibrated to be different and so you will have to see with a stove thermometer in different places where the best place is to put your food so not to have it come out wrong. good luck.