GalMutzafy is right you need to stabilize the dream first.

A fundamental misunderstanding is that you are either lucid or non-lucid. Lucidity is not a light switch, that it is either turned on or off. it's a spectrum and it can range from complete unconsciousness (non-lucid) to semi-lucidity to full lucidity.

Dream stabilization techniques (like rubbing your palms together) can help to increase your lucidity. This will improve the visual clarity of your dreams and allow for more dream control (you'll be able to speak).