[shoffing]

Thanks for the replies, we think we found the problem. We got voltage readings from the trackers and the results were surprising. I'm not 100% sure about the precise voltages, but I think they were giving us something like 0.35 volts when they were on the line, and 0.75 volts when they were off the line. The electrical lead tried to explain why this might be the problem, but it went right over my head. He hooked up a resistor to the simple circuit he had and the voltages then changed to 0.35 when they were on and 18 when they were off. We're hoping that the reason it wasn't working was because there was such a minor difference in voltage between the 2 states.

The one thing that really bugs me (as well as our electrical subteam) is that there wasn't a single bit of documentation stating that we might need a resistor to get the trackers to work. I looked through the programming forum, and from what it looks like we were the only team experiencing this problem. Are any of you guys using a resistor with your trackers? If so, how did you realize that you needed to?

I'll get back to you guys tonight after we see if this fixed it.