what is up with the ACT button?

Kay.
 
I'm having probs understanding the ACT control stuff. I know it can be used to do things in your software externally, but i'm not sure how to set it up.
 
What I noticed is when the vs-100 is plugged in-the ACT button at top left will not even light up! At first I thought it was broken and was gonna call the dude who sold me the unit and try to either send it back or maybe get a refund or partial refund. But then I unplugged the USB cable from the vs-100, first-while turning it off and then while it was still on.
 
When I turned it off, the DAW red button light came on to indicate you can record wave into your SD card, etc..
 
And when I hit the ACT button then-it will finally light up-orange. but then it says "V," for V-link. So does that mean the ACT button is always "ON?" It won't light up at all when I have the vs100 plugged into the computer. Is it supposed to?
 
I looked in the vs100 properties page in Sonar VS and it said that ACT was full or enabled I guess. But I couldn't change anything in the menu box. And hitting the ACT button didn't do anything either. Hope I didn't get some messed up unit.