Working Flipbook field goes red when I change the texture ID, why?

Hi,

I have a working flipbook, 4x4 grid that works correctly.

When I change the texture ID to another image I uploaded that is also a 4x4 grid, the flipbook setting goes red and I cannot select the flipbook. The new image I think is 500 x 500

How can I fix this?

Working one

flipingbook :slight_smile: goes red

I can then see the image that show the whole big 4 x 4 full image, instead of it doing a flipbook looped single image piece.

Thanks!