Sound Trouble

[Danrobin]

Hi I'm having trouble getting sound to record with the video. What I'm using for sound is a Mackie 24 channel mixing board. The board is connected to the computer via the USB port. It does work with my audio software Mixcraft Recording Studio. I have tried all the inputs and outputs of the mixing board with no luck. But if I play a mp3 file while recording video it works great. Does anyone have a idea of what I'm doing wrong? Thanks for any input on this problem