"AE error: unsafe operation attempted"

[O***@adobeforums.com]

Never seen this error window before. Most times AE flashes it a time or two, and then does what I want and works okay. Other times it just keeps on popping up until I Ctrl-Alt-Del its tucas.

I'm trying to drive the current frame of one animation with the intensity of another. Just to complicate things, I'm trying to do it 300 times to a grid of them.

So, I have a 2 second precomp 40px x 40px basically of a square growing. I applied this expression it's time remap:

Tester = thisComp.layer("DriveLayer");
Intensity = Tester.sampleImage(transform.position, [1,1]) [0];
linear(Intensity, 0, 100, 0, 60)

The idea being that each square will animate based on the red intensity of the DriveLayer pixel under it. It seems to work, aside from being unsafe and crashing sometimes. How can I clean it up?

Also, since I have a grid of these biddies I would like to just write the expression once, and then target all the duplicates to that so I can edit them all easily. But if I pickwhip the duplicate square's time remap to the original, square number 2 doesnt account for its new position?

(I tend to think this is kind of a slick setup, but truth be told, I have no idea what I am doing, and help is appreciated)

[M***@adobeforums.com]

Expressions can be copy&pasted en masse using the "Copy Expression only" function. The "unsafeness" may be caused by the 1 pixel sample area and how you directly asociate it with the position. Would require some deeper look...

Mylenium