Floating Debris Index raster band problem.

I am new to atmospheric processing and I am trying to apply FDI Index to the sentinel-2 imagery. I am using SNAP for the preprocessing.

What I have done is apply NDVI to the original file I got from copernicus website, it created a new image as well as a new file entirely. Then, I am trying to apply the FDI to the new imagery now, and it says ‘Referenced raster must all be of the same size’. How do I work that out??

There are several posts dealing with this – please use the search tool to find them, and post a followup if none of the solutions work for you.