Det J is negative

my typical set looks somehow like this

NodeReordering.exe -m 1 V1_SubsurfaceMesh.vtu V2_SubsurfaceMesh.vtu

identifySubdomains.exe -m V2_SubsurfaceMesh.vtu -s 1 -o BC_ -- RiverLineNetworkMapped.vtu

Finding the correct number for -s is sometimes tricky as well.