WHY CAN'T SKYPE VIDEO CALL WORK?

For skype when i use my cam it doesn't work, yet alone it doesn't give me the option to video call. I even go to preferences and it won't allow me to change my camera. I've uninstalled it and installed it 3 times and nothing has worked. I really miss seeing my family on skype and i can't see them. All i want is an update or soultion so i can go back to seeing my family.