I can't hear yooouu

Our final for physics is to create our own device that correlates to the material studied this semester. I began thinking this would be super easy project but 29837847825350 dollars later I've finally gotten a kit to work, even though one of the microphones are a dud. I began wanting to make a laser microphone because the video and website made it sound so easy but turns out NOTHING WORKS! I don't know if it's my photocell or the photo transmitter that aren't working or the cables I've connected them to but in the end, both are just useless. It's so annoying and disappointing. I got the sound amplifier kit working at the moment so hopefully it stays that way until we have to present them in a couple of weeks...