I see a couple things that I wonder about. First, the majority of the larger area of zone B is partially blocked by tree limbs. You may need to reduce your object size (maybe try something like 300) to detect something behind those limbs. Also keep in mind that in the warm season, leaves on that tree are going to block most of detection zone B. I also don't see any need for the small slivers of zone B on the left and right edges. They are not wide enough for an object to meet your size and object travel distance requirements so I doubt anything would be triggered there. My first suggestion would be to widen the top left of Zone B so that it extends about twice as far to the right. That will give the detector more time to meet the motion requirements of size, 100 pixels of movement (which I think I would reduce to 50 in a zone crossing environment too), and your make time of .7 seconds. Start with more "lax" requirements maybe, and then fine tune them as needed:
- Increase the size of the upper left corner of zone B, extending it farther to the right
- Remove the slivers of zone B on the left and right as I don't think they'll do anything: not wide enough to trigger motion in zone B
- Reduce the travel distance to 50 pixels
- Reduce your object size to 300
- Reduce the make time to .5 seconds: an object moving quickly through zone B won't have much time until it gets to zone A
Keep in mind that as written (B>A) you will not get objects moving from right to left. Don't know if that's important. Another thing to remember is that once that tree gets leaves on it, you may end up with false triggers because BI doesn't really keep track of single objects. The way it works (B>A) is that it will trigger an alert when something happens in zone B, followed by something happening in zone A. So it could pick up the tree in zone B moving due to wind, followed by a cat walking in zone A. And that will trigger it.
Mike