realityvideoman ,
You didn't mention what model camera you have, but if it's not one of the new video-capable cameras, it can send only one picture. If you have it set to burst, it will send the LAST picture of the burst.
The trigger interval is the "quiet time" between when the camera is finished sending a picture and when it can take another. For security, you'll probably want to run that on 0 trigger interval.