If your bread is not rising properly, there could be a few possible reasons. First, make sure the yeast is fresh and active. If it's expired or has been stored improperly, it may not activate properly. Additionally, the temperature and humidity of the environment can affect the rise of the dough. Too cool of a temperature or low humidity can slow down the rise, while too high of a temperature or high humidity can cause the dough to over-rise and collapse.