If no picture is showing up on your computer monitor or projecting onto your smart board:

There are 3 parts to making your computer screen show up on your projector which goes to your smart board. 1 is the computer monitor, 2 is the amplifier, and 3 is the document camera. The document camera acts as a secondary amplifier so if the document camera is off, nothing will show on the screen. If the amplifier is unplugged, nothing will show on the screen as well. The diagram below shows which cables go where and can be used as a troubleshooting guide