I'm confused about the results that I get from the raster calculator in QGIS.

I'm trying to delete the cells of a raster who are prone to flooding. However, a part of my raster is wrongly classified as a high risk area, thus for this part I want to use the original raster and for the other areas I want to delete the cells with a high flood risk.

Below, I added my rasterized polygone layer, red is the part that I want to keep from the original layer and has a value of -2, the rest is -1. This layer is my original layer:

enter image description here

and this is the raster adapted for flood risk:

enter image description here

White areas are areas without data.

In the calculator I typed:

("rasterized" = -2) * "original layer" + ("rasterized" = -1) * "adapted layer"

However, it returns the adapted layer only. Also when I switch the values, I get the adapted layer.

When I make two seperate layers: one with the part of the original layer that I want and one with the part of the adapted layer, this formulas seems to work, but again when I add them I only get the adapted layer.

Does anyone has an idea of what I might be doing wrong?

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